Cambridge International AS &A Level Mathematics 9709 syllabus for 2023, 2024 and 2025. 5 List of formulae and statistical tables {MF19) PURE MATHEMATICS Mensuration Volume of sphere= fnr 3 Surface area of sphere = 4nr 2 Volume of cone or pyramid = ½x base area x height Area of curved surface of cone = nr x slant height Arc length of circle = r0 ( 0 in radians) Area of sector of circle = ½r 2 0 ( 0 in radians) Algebra For the quadratic equation ax 2 +bx+ c = 0: -b± ✓b 2 -4ac x=-----2a For an arithmetic series: Un =a+ (n - l)d , Sn =½n(a+l)=½n{2a+(n-l)d} For a geometric series: Un =ar n-1 , S =_!!:_ 1-r 00 (lrl<l) Binomial series: and (1 + X Back to contents page • (n)r = r!(n-r)! nl r = 1+ nx + -n(n-2!-1) -x 2 n(n - l)(n - 2) + - - - - - x 3 + ... ' where n is rational and 3! IX I< 1 www.cambridgeinternational.org/alevel 39 Cambridge International AS & A Level Mathematics 9709 syllabus for 2023, 2024 and 2025. List of formulae and statistical tables (MF19) Trigonometry sin0 tan0=-cos0 cos 2 0 + sin 2 0 ==1, cot 2 0 + I = cosec 2 0 l+tan 2 0=sec 2 0, sin(A ± B) = sinAcosB ± cosAsinB cos(A ± B) = cosAcosB + sinAsinB tanA±tanB tan(A ± B) = - - - - l + tanAtanB sin2A = 2sinAcosA cos2A = cos 2 A-sin 2 A= 2cos 2 A-1 = 1-2sin 2 A tan2A = 2 tan A 1-tan2 A Principal values: 0 ~cos -1 x ~ n, Differentiation f(x) f'(x) nx lnx n-1 1 X sinx cosx cosx -smx tanx sec 2 x secx secxtanx cosecx -cosecxcotx cotx -cosec 2 x 1 l+x 2 UV du dv v-+udx dx u du dv v--udx dx V v2 dy dy dx If x=f(t) and y =g(t) then-=-+dx dt dt 40 www.cambridgeinternational.org/alevel Back to contents page Cambridge International AS & A Level Mathematics 9709 syllabus for 2023, 2024 and 2025. List of formulae and statistical tables (MF19) Integration (Arbitrary constants are omitted; a denotes a positive constant.) f f(x)dx f(x) Xn+l xn (n :;t: -1) n+I 1 Inlxl X ex ex smx -cosx cosx smx sec 2 x tanx 1 1 -1(X) ~tan ~ x2 +a2 1 2 X -a 2 1 2 a -x 2 1x-a1 -1l n -2a x+a (x> a) _l ln1~1 2a a-x fu dvdx dx=uv- f v dudx dx dx = Inlf(x)I f f'(x) f(x) Vectors If a= a1i + a2 j + a3k and b = b1i + b2 j + b3k then Back to contents page www.cambridgeinternational.org/alevel 41 Cambridge International AS & A Level Mathematics 9709 syllabus for 2023, 2024 and 2025. List of formulae and statistical tables (MF19) FURTHER PURE MATHEMATICS Algebra Summations: ~:> =½n(n+l), n n r=I n ~:> 2 = ¼n(n + 1)(2n + 1), ~:>3 =¼n2(n+l)2 r=I r=I Maclaurin's series: x2 xr f(x) = f(O) + xf'(O) +-f"(O) + ... +-f(r) (0) + ... 2! r! 2 r ex =exp ( x ) = l + x +X- + ... +X- + ... 2! r! x2 ln(l + x) = x - . X3 x3 (allx) xr + - - ... + (-1y+1 - + ... r 2 3 X5 r (allx) 2r 4 cos x = l - ~ + ~ - ... + (-1r _x_ + ... 2! 4! (2r)! X3 < X < 1) X2r+I smx=x--+-- ... +(-1) - - - + ... 3! 5! (2r + 1)! 2 (-1 X5 (allx) X2r+I tan- 1 x = x - - + - - ... + ( - l Y - - + ... 3 5 2r+ 1 . X3 X5 X2r+I smhx = x +- +- + ... + - - - + ... 3! 5! (2r+l)! x2 x4 (allx) x2r coshx = 1 + - + - + ... + - - + ... 2! 4! (2r)! tanh -1 (allx) 3 5 2r+l X X X x = x + - + - + ... + - - + ... 3 5 (-l<x<l) 2r +l Trigonometry If t = tan½x then: . 2t sinx=-2 l-t 2 cosx=-2 and l+t Hyperbolic Junctions cosh 2 x - sinh 2 x = l , l+t sinh 2x = 2 sinh x cosh x cosh 2x = cosh 2 x + sinh 2 x , sinh - I x = In(x + ,Jx 2 + 1) cosh- 1 x=ln(x+ ✓x 2 -1) (l+x) _ 11- n tanh _1 X -2 42 www.cambridgeinternational.org/alevel l-x (x ~ 1) (Ix I< 1) Back to contents page Cambridge International AS & A Level Mathematics 9709 syllabus for 2023, 2024 and 2025. List of formulae and statistical tables (MF19) Differentiation f(x) f'(x) 1 sin- 1 x ✓1-x 2 1 cos- 1 x ✓1-x 2 sinhx coshx coshx sinhx tanhx sech 2 x sinh-l X 1 ✓I+x 2 1 cosh- 1 x -J x 2 -1 1 l-x 2 tanh-l X Integration (Arbitrary constants are omitted; a denotes a positive constant.) f(x) ff(x)dx secx lnlsecx+tanxl =lnltan(½x+¼n)I cosecx - ln cosec x + cot x = ln tan(½ x) sinhx coshx coshx sinhx sech 2 x tanhx 1 -Jaz -xz 1 -Jx2 -a2 1 -Jaz +xz Back to contents page I I I I (O<x<n) . -1 (XJ a sm cosh -t(XJ ~ (x>a) 1(~J sinh- www.cambridgeinternational.org/alevel 43 Cambridge International AS & A Level Mathematics 9709 syllabus for 2023, 2024 and 2025. List of formulae and statistical tables (MF19) MECHANICS Uniformly accelerated motion v=u +at, s =ut +l.at 2 s =½(u +v)t, 2 ' v2 =u 2 +2as FURTHER MECHANICS Motion of a projectile Equation of trajectory is: y=xtan0- gx2 2 2 2V cos 0 Elastic strings and springs E=AX2 21 Motion in a circle For uniform circular motion, the acceleration is directed towards the centre and has magnitude or r Centres of mass of uniform bodies Triangular lamina: f along median from vertex Solid hemisphere ofradius r: ¾r from centre Hemispherical shell of radius r: ½r from centre Circular arc of radius rand angle 2a: rsma from centre a 2rsina .i:: • 1ar sector of rad.ms r and ang1e 2 a: C1rcu - - 1-rom centre 3a Solid cone or pyramid of height h: 44 www.cambridgeinternational.org/alevel ¾h from vertex Back to contents page Cambridge International AS & A Level Mathematics 9709 syllabus for 2023, 2024 and 2025. List of formulae and statistical tables (MF19) PROBABILITY & STATISTICS Summary statistics For ungrouped data: LX x=-, n standard deviation = ✓L(x: x)2 = ✓~ 2 x - 2 For grouped data: standard deviation = E(x - X)' f = JD-' f Lf Lf x' Discrete random variables E(X)=LXp, Var(X) = LX 2 p-{E(X)} 2 For the binomial distribution B(n,p): a- 2 = np(I - p) µ=np, For the geometric distribution Geo(p): 1 p Pr= p(I- py-1' µ=- For the Poisson distribution Po(,1,) Continuous random variables f f Var(X) = x 2 f(x) dx-{E(X)} 2 E(X) = xf(x) dx, Sampling and testing Unbiased estimators: LX x=-, n s2 = L(x-x) 2 =-1-(LX 2 n-1 n-1 _ (LX) 2 ) n Central Limit Theorem: Approximate distribution of sample proportion: Back to contents page www.cambridgeinternational.org/alevel 45 Cambridge International AS & A Level Mathematics 9709 syllabus for 2023, 2024 and 2025. List of formulae and statistical tables (MF19) FURTHER PROBABILITY & STATISTICS Sampling and testing Two-sample estimate of a common variance: L(x1 -:x1)2 +L(x2 -:x2 )2 2 s =--------nl +n 2 -2 Probability generating functions Gx(t) = E(tx), 46 www.cambridgeinternational.org/alevel E(X) = G'.r(l), Var(X) = G'.'r(l) + G'.r(l)- {G'.r(1)} 2 Back to contents page Cambridge International AS & A Level Mathematics 9709 syllabus for 2023, 2024 and 2025. List of formulae and statistical tables (MF19) THE NORMAL DISTRIBUTION FUNCTION If Z has a normal distribution with mean O and variance 1, then, for each value of z, the table gives the value of <l>(z), where <l>(z) = P(Z,..; z). LI For negative values of z, use <l>(-z) = 1 - <l>(z). z 0 1 2 4 3 5 6 7 8 9 1 2 3 4 8 8 12 12 12 16 20 24 28 16 20 24 28 15 19 23 27 0.5239 0.5279 0.5319 0.5359 0.5636 0.5675 0.5714 0.5753 0.6026 0.6064 0.6103 0.6141 4 4 4 0.6406 0.6443 0.6480 0.6517 0.6772 0.6808 0.6844 0.6879 4 4 0.7 0.8 0.9 0.6915 0.6950 0.6985 0.7019 0.7054 0.7088 0.7257 0.7291 0.7324 0.7357 0.7389 0.7422 0.7580 0.7611 0.7642 0.7673 0.7704 0.7734 0.7881 0.7910 0.7939 0.7967 0.7995 0.8023 0.8159 0.8186 0.8212 0.8238 0.8264 0.8289 0.7123 0.7157 0.7190 0.7224 0.7454 0.7486 0.7517 0.7549 0.7764 0.7794 0.7823 0.7852 0.3 0.4 6 7 8 9 ADD 0.5000 0.5040 0.5080 0.5120 0.5160 0.5199 0.5398 0.5438 0.5478 0.5517 0.5557 0.5596 0.5793 0.5832 0.5871 0.5910 0.5948 0.5987 0.6179 0.6217 0.6255 0.6293 0.6331 0.6368 0.6554 0.6591 0.6628 0.6664 0.6700 0.6736 0.0 0.1 0.2 5 8 7 32 36 32 36 31 35 15 19 22 26 30 34 14 18 22 25 29 32 7 11 11 3 3 7 7 10 10 0.8051 0.8078 0.8106 0.8133 0.8315 0.8340 0.8365 0.8389 3 3 3 6 5 5 9 8 8 1.0 0.8413 0.8438 0.8461 0.8485 0.8508 0.8531 0.8554 0.8577 0.8599 0.8621 2 5 12 14 16 19 21 0.8643 0.8849 0.9032 0.9192 0.8830 0.9015 0.9177 0.9319 2 2 2 1 4 4 3 3 7 6 6 5 4 9 1.1 1.2 1.3 1.4 8 7 6 6 10 12 14 11 13 10 11 8 10 16 15 13 11 18 17 14 13 1.5 1.6 1.7 1.8 1.9 0.9332 0.9345 0.9357 0.9452 0.9463 0.9474 0.9554 0.9564 0.9573 0.9641 0.9649 0.9656 0.9713 0.9719 0.9726 0.9418 0.9429 0.9441 1 2 4 1 1 2 2 6 5 4 1 1 1 1 3 3 2 2 5 4 4 3 2 4 3 7 6 5 4 4 8 7 6 5 4 10 8 7 6 5 11 0.9525 0.9535 0.9545 0.9616 0.9625 0.9633 0.9693 0.9699 0.9706 0.9756 0.9761 0.9767 2.0 2.1 2.2 0.9772 0.9778 0.9783 0.9788 0.9793 0.9798 0.9803 0.9808 0.9812 0.9817 0.9821 0.9826 0.9830 0.9834 0.9838 0.9842 0.9846 0.9850 0.9854 0.9857 0.9861 0.9864 0.9868 0.9871 0.9875 0.9878 0.9881 0.9884 0.9887 0.9890 0 1 1 1 1 1 1 2 2 1 2 2 2 3 2 2 3 4 0 0 3 2 3 3 4 4 3 2.3 2.4 0.9893 0.9896 0.9898 0.9901 0.9904 0.9906 0.9909 0.9911 0.9913 0.9916 0.9918 0.9920 0.9922 0.9925 0.9927 0.9929 0.9931 0.9932 0.9934 0.9936 0 0 1 0 1 1 1 1 1 1 2 1 2 1 2 2 2 2 2.5 2.6 2.7 0.9938 0.9940 0.9941 0.9943 0.9945 0.9946 0.9948 0.9949 0.9951 0.9952 0.9953 0.9955 0.9956 0.9957 0.9959 0.9960 0.9961 0.9962 0.9963 0.9964 0.9965 0.9966 0.9967 0.9968 0.9969 0.9970 0.9971 0.9972 0.9973 0.9974 0 0 0 0 0 0 0 0 0 1 0 0 1 1 0 1 1 1 1 1 1 1 1 1 1 1 1 2.8 2.9 0.9974 0.9975 0.9976 0.9977 0.9977 0.9978 0.9979 0.9979 0.9980 0.9981 0.9981 0.9982 0.9982 0.9983 0.9984 0.9984 0.9985 0.9985 0.9986 0.9986 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 0 0.5 0.6 0.8665 0.8869 0.9049 0.9207 0.8686 0.8888 0.9066 0.9222 0.8708 0.8907 0.9082 0.9236 0.8729 0.8925 0.9099 0.9251 0.8749 0.8944 0.9115 0.9265 0.8770 0.8962 0.9131 0.9279 0.9370 0.9382 0.9394 0.9406 0.9484 0.9495 0.9505 0.9515 0.9582 0.9591 0.9599 0.9608 0.9664 0.9671 0.9678 0.9686 0.9732 0.9738 0.9744 0.9750 0.8790 0.8980 0.9147 0.9292 0.8810 0.8997 0.9162 0.9306 14 17 20 24 27 31 13 16 19 23 26 29 12 15 18 21 24 27 11 14 10 13 9 8 7 16 19 22 25 15 18 20 23 9 8 6 5 Critical values for the normal distribution If Z has a normal distribution with mean O and variance 1, then, for each value ofp, the table gives the value of z such that P(Z,..; z) =p. p 0.75 0.90 0.95 z 0.674 1.282 1.645 Back to contents page 0.975 0.99 0.995 0.9975 0.999 0.9995 1.960 2.326 2.576 2.807 3.090 3.291 www.cambridgeinternational.org/alevel 47 Cambridge International AS & A Level Mathematics 9709 syllabus for 2023, 2024 and 2025. List of formulae and statistical tables (MF19) CRITICAL V ALOES FOR THE t-DISTRIBUTION If T has a t-distribution with v degrees of freedom, then, for each pair of values of p and v, the table gives the value oft such that: P(T <;. t) = p. 0.75 0.90 0.95 0.975 0.99 0.995 0.9975 0.999 0.9995 v= 1 1.000 3.078 6.314 12.71 31.82 63.66 127.3 318.3 636.6 2.920 2.353 2.132 4.303 3.182 2.776 6.965 4.541 3.747 9.925 5.841 4.604 14.09 7.453 5.598 22.33 10.21 7.173 31.60 12.92 8.610 2.015 1.943 2.571 2.447 2.365 3.365 3.143 2.998 4.032 3.707 5.894 5.208 4.785 6.869 5.959 2.306 2.262 2.896 2.821 3.499 3.355 3.250 4.773 4.317 4.029 3.833 3.690 4.501 4.297 2.764 2.718 2.681 2.650 2.624 3.169 3.106 3.055 3.012 2.977 3.581 3.497 3.428 3.372 3.326 4.144 4.025 3.930 3.852 3.787 4.587 4.437 4.318 4.221 4.140 p 2 0.816 1.886 3 4 0.765 0.741 1.638 1.533 5 6 0.727 0.718 0.711 1.476 1.440 1.415 0.706 0.703 1.397 1.383 10 11 12 13 14 0.700 0.697 0.695 0.694 0.692 1.372 1.363 1.356 1.350 1.345 1.812 1.796 1.782 1.771 1.761 2.228 2.201 2.179 2.160 2.145 15 16 17 18 0.691 0.690 0.689 0.688 1.341 1.337 1.333 1.330 1.753 1.746 1.740 1.734 2.131 2.120 2.110 2.101 2.602 2.583 2.567 2.552 2.947 2.921 2.898 2.878 3.286 3.252 3.222 3.197 3.733 3.686 3.646 3.610 4.073 4.015 3.965 3.922 19 0.688 1.328 1.729 2.093 2.539 2.861 3.174 3.579 3.883 20 21 22 0.687 0.686 1.325 1.323 1.321 1.725 1.721 1.717 2.086 2.080 2.074 2.528 2.518 2.508 2.845 2.831 2.819 3.153 3.135 3.119 3.552 3.527 3.850 3.819 3.792 0.685 1.319 1.318 1.714 1.711 2.069 2.064 2.500 2.492 2.807 2.797 3.104 3.091 25 26 27 0.684 0.684 0.684 1.316 1.315 1.314 1.708 1.706 1.703 2.060 2.056 2.052 2.485 2.479 2.473 2.787 2.779 2.771 28 29 0.683 0.683 1.313 1.311 1.701 1.699 2.048 2.045 2.467 2.462 30 40 60 120 0.683 0.681 0.679 0.677 1.310 1.697 1.684 1.671 1.658 2.042 1.303 1.296 1.289 2.021 2.000 1.980 00 0.674 1.282 1.645 1.960 7 8 9 23 24 48 0.686 0.685 www.cambridgeinternational.org/alevel 1.895 1.860 1.833 3.505 3.485 5.408 5.041 4.781 3.467 3.768 3.745 3.078 3.067 3.057 3.450 3.435 3.421 3.725 3.707 3.689 2.763 2.756 3.047 3.038 3.408 3.396 3.674 3.660 2.457 2.750 2.423 2.390 2.358 2.704 2.660 2.617 3.030 2.971 2.915 2.860 3.385 3.307 3.232 3.160 3.646 3.551 3.460 3.373 2.326 2.576 2.807 3.090 3.291 Back to contents page Cambridge International AS & A Level Mathematics 9709 syllabus for 2023, 2024 and 2025. List of formulae and statistical tables (MF19) CRITICAL VALUES FOR THE If Xhas a z 2 -DISTRIBUTION z 2 -distribution with v degrees of freedom then, for each pair of values ofp and v, the table gives the value of x such that P(X ~ x) = p. p .t p 0.01 0.025 0.05 0.9 0.95 0.975 0.99 0.995 0.999 v= 1 2 3 4 0.0 3 1571 0.02010 0.1148 0.2971 0.0 39821 0.05064 0.2158 0.4844 0.0 23932 0.1026 0.3518 0.7107 2.706 4.605 6.251 7.779 3.841 5.991 7.815 9.488 5.024 7.378 9.348 11.14 6.635 9.210 11.34 13.28 7.879 10.60 12.84 14.86 10.83 13.82 16.27 18.47 5 6 7 8 9 0.5543 0.8721 1.239 1.647 2.088 0.8312 1.237 1.690 2.180 2.700 1.145 1.635 2.167 2.733 3.325 9.236 10.64 12.02 13.36 14.68 11.07 12.59 14.07 15.51 16.92 12.83 14.45 16.01 17.53 19.02 15.09 16.81 18.48 20.09 21.67 16.75 18.55 20.28 21.95 23.59 20.51 22.46 24.32 26.12 27.88 10 11 12 13 14 2.558 3.053 3.571 4.107 4.660 3.247 3.816 4.404 5.009 5.629 3.940 4.575 5.226 5.892 6.571 15.99 17.28 18.55 19.81 21.06 18.31 19.68 21.03 22.36 23.68 20.48 21.92 23.34 24.74 26.12 23.21 24.73 26.22 27.69 29.14 25.19 26.76 28.30 29.82 31.32 29.59 31.26 32.91 34.53 36.12 15 16 17 18 19 5.229 5.812 6.408 7.015 7.633 6.262 6.908 7.564 8.231 8.907 7.261 7.962 8.672 9.390 10.12 22.31 23.54 24.77 25.99 27.20 25.00 26.30 27.59 28.87 30.14 27.49 28.85 30.19 31.53 32.85 30.58 32.00 33.41 34.81 36.19 32.80 34.27 35.72 37.16 38.58 37.70 39.25 40.79 42.31 43.82 20 21 22 23 24 8.260 8.897 9.542 10.20 10.86 9.591 10.28 10.98 11.69 12.40 10.85 11.59 12.34 13.09 13.85 28.41 29.62 30.81 32.01 33.20 31.41 32.67 33.92 35.17 36.42 34.17 35.48 36.78 38.08 39.36 37.57 38.93 40.29 41.64 42.98 40.00 41.40 42.80 44.18 45.56 45.31 46.80 48.27 49.73 51.18 25 30 40 50 60 11.52 14.95 22.16 29.71 37.48 13.12 16.79 24.43 32.36 40.48 14.61 18.49 26.51 34.76 43.19 34.38 40.26 51.81 63.17 74.40 37.65 43.77 55.76 67.50 79.08 40.65 46.98 59.34 71.42 83.30 44.31 50.89 63.69 76.15 88.38 46.93 53.67 66.77 79.49 91.95 52.62 59.70 73.40 86.66 99.61 70 80 90 100 45.44 53.54 61.75 70.06 48.76 57.15 65.65 74.22 51.74 60.39 69.13 77.93 85.53 96.58 107.6 118.5 90.53 101.9 113.1 124.3 95.02 106.6 118.1 129.6 100.4 112.3 124.1 135.8 104.2 116.3 128.3 140.2 112.3 124.8 137.2 149.4 Back to contents page www.cambridgeinternational.org/alevel 49 Cambridge International AS & A Level Mathematics 9709 syllabus for 2023, 2024 and 2025. List of formulae and statistical tables (MF19) WILCOXON SIGNED-RANK TEST The sample has size n. P is the sum of the ranks corresponding to the positive differences. Q is the sum of the ranks corresponding to the negative differences. Tis the smaller of P and Q. For each value of n the table gives the largest value of Twhich will lead to rejection of the null hypothesis at the level of significance indicated. Critical values of T Level of significance One-tailed Two-tailed n=6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 0.05 0.1 2 3 5 8 10 13 17 21 25 30 35 41 47 53 60 0.025 0.05 0 2 3 5 8 10 13 17 21 25 29 34 40 46 52 0.01 0.02 0.005 0.01 0 1 3 5 7 9 12 15 19 23 27 32 37 43 0 1 3 5 7 9 12 15 19 23 27 32 37 For larger values of n, each of P and Q can be approximated by the normal distribution with mean and variance so ¼n( n + 1) J4 n(n + 1)(2n + 1). www.cambridgeinternational.org/alevel Back to contents page Cambridge International AS & A Level Mathematics 9709 syllabus for 2023, 2024 and 2025. List of formulae and statistical tables (MF19) WILCOXON RANK-SUM TEST The two samples have sizes m and n, where m ,.;;; n. Rm is the sum of the ranks of the items in the sample of size m. Wis the smaller of Rm and m(n + m + 1) - Rm. For each pair of values of m and n, the table gives the largest value of W which will lead to rejection of the null hypothesis at the level of significance indicated. Critical values of W One-tailed Two-tailed 0.05 0.1 n 3 4 5 6 7 8 9 10 6 6 7 8 8 9 10 10 One-tailed Two-tailed 0.05 0.1 n 7 8 9 10 39 41 43 45 0.025 0.05 m=3 0.01 0.02 - - - - 6 7 7 8 8 9 - 0.025 0.05 m=7 36 38 40 42 - 6 6 7 7 0.05 0.1 11 12 13 14 15 16 17 0.01 0.02 0.05 0.1 34 35 37 39 51 54 56 Level of significance 0.025 0.01 0.05 0.025 0.1 0.02 0.05 0.05 m=4 m=5 10 11 12 13 14 14 15 0.05 0.1 0.025 0.05 m=6 0.01 0.02 16 17 18 19 20 21 28 29 31 33 35 26 27 29 31 32 24 25 27 28 29 0.01 0.02 0.05 0.1 0.025 0.05 m= 10 0.01 0.02 59 61 82 78 74 - 10 11 11 12 13 13 19 20 21 23 24 26 17 18 20 21 22 23 Level of significance 0.025 0.01 0.05 0.025 0.1 0.02 0.05 0.05 m=8 m=9 49 51 53 0.01 0.02 45 47 49 For larger values of m and n, the normal distribution with mean 66 69 62 65 ½m( m + n + 1) and variance 1mn( m + n + 1) 1 should be used as an approximation to the distribution of Rm. Back to contents page www.cambridgeinternational.org/alevel 51