STATISTICS ─CHAPTER 6 TEST
Name:
1. A continuous random variable is a random variable that can assume:
a. only countable values
c. any value in one or more intervals
b. only discrete frequencies
d. no continuous random frequency
2. For a continuous random variable x, the probability that x assumes a value in an interval is:
a. in the range zero to 1 b. greater than 1
c. less than zero
d. greater than 2
3. For a continuous random variable x, the area under the probability distribution curve between
any two points is always:
a. greater than 1
b. less than zero
c. equal to 1
d. in the range 0 and 1
4. For a continuous random variable x, the total probability of all (mutually exclusive) intervals
within which x can assume a value is:
a. less than 1
b. greater than 1
c. equal to 1
d. between 0 and 1
5. The total area under the probability distribution curve of a continuous random variable x is:
a. less than 1
b. greater than 1
c. equal to 1
d. between 0 and 1
6. The probability that a continuous random variable x assumes a single value is always:
a. less than 1
b. greater than zero
c. equal to zero
d. between zero and 1
7. Which of the following is not a characteristic of the normal distribution?
a. The total area under the curve is 1.0
c. The curve is symmetric about the mean
b. The value of the mean is 1.0
d. The two tails of the curve extend indefinitely
8. The total area under a normal distribution curve to the left of the mean is always:
a. equal to 1
b. equal to zero
c. equal to .5
d. greater than .5
9. For the standard normal distribution the mean is____ and the standard deviation is___.
a. 1; zero
b. .5;.5
c. zero; 1
d. 1; 1
10. For a normal distribution, the z value for an x value that is to the left of the mean is always:
a. equal to zero
b. negative
c. less than 1
d. positive
11. For the standard normal distribution, the area between z = 0 and z = 1.97 is:
a. .4713
b. .4761
c. .4745
d. .4756
12. For the standard normal distribution, the area between z = 0 and z = –2.13 is:
a. .4834
b. .4821
c. .4893
d. .4838
13. For the standard normal distribution, the area to the right of z = –.78 is:
a. .2177
b. .7177
c. .7823
d. .2823
14. For the standard normal distribution, the area to the left of z = –l.35 is:
a. .4115
b. .0885
c. .9115
d. .5855
15. For the standard normal distribution, the area between z = .79 and z = 2.67 is:
a. .2110
b. .4962
c. .2852
d. .7814
16. Let x have a normal distribution with a mean of 40 and a standard deviation of 5. The z value
for x = 52 is:
a. 2.00
b. 1.50
c. –1.75
d. .80
17. Let x have a normal distribution with a mean of 60 and a standard deviation of 4. The z value
for x = 53 is:
a. 1.75
b. 1.25
c. –1.75
d. –1.25
18. The GMAT scores of all examinees who took that test this year, are normally distributed with
a mean of 420 and a standard deviation of 40. The probability that the score of a randomly
selected examinee is between 400 and 480 is:
a. .624 7
b. .2417
c. .6915
d .9332
19. The heights of all female college basketball players are normally distributed with a mean of
68 inches and a standard deviation of 2 inches. The probability that the height of a randomly
selected female college basketball player is more than 66.5 inches is:
a. .2734
b. .2266
c. .7734
d. .2289
20. If the area under the standard normal curve from 0 to z is .3508 and z is positive, then z is:
a. 1.00
b. 1.40
c. 1.04
d. 2.04
21. If the area under the standard normal curve from 0 to z is .4850 and z is negative, then z is:
a. –2.17
b. –2.10
c. –3.03
d. –1.21
22. Usually the binomial distribution is approximated by the normal distribution when:
a. the sample size is at least 30
c. np and nq are both greater than 5
b. np and nq are both less than 5
d. nx is greater than 30
23. Sixty percent of all adults are in favor of abolishing the sales tax and increasing the income
tax. The probability that in a random sample of 400 adults, exactly 250 will be in favor of
abolishing the sales tax and increasing the income tax is approximately:
a. .2598
b. .4162
c. .0237
d. .3201
24. Football is the favorite sport to watch on television for 40% of all adults. The probability that
in a random sample of 500 adults, 193 or more will say football is their favorite sport to
watch on television is approximately:
a. .2517
b. .2483
c. . 74 83
d. .7517
25. The value of z so that the area under the standard normal curve in the left tail is .015 is:
a. –2.07
b. –2.58
c. –2.17
d. –1.96
26. The net weights of all boxes of Top Taste cookies are normally distributed with a mean of
32.07 ounces and a standard deviation of .11 ounces. The probability that the net weight of a
randomly selected box of such cookies is between 39.96 and 32.18 ounces is:
a. .0876
b. .6826
c. .3413
d. .0438
27. The net weights of all boxes of Top Taste cookies are normally distributed with a mean of
32.07 ounces and a standard deviation of .11 ounces. The probability that the net weight of a
randomly selected box of such cookies is between 31.81 and 31.94 ounces is:
a. .1099
b. .8719
c. .4909
d. .9332
CHAPTER 6 TEST
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