Solving a testing of hypothesis problem using steps given on page 545
We solve the problem 10.64 from the text book
Step 1
In this problem the variable measured is
X = rate of uptake of radio-labeled amino acid in a bacteria culture with nitrates
 = mean rate of uptake radio-labeled amino acid in all bacteria cultures with nitrates
Step 2
H0 (Null hypothesis) :  = 8000
Step 3
Ha (alternative hypothesis) :  < 8000
Step 4
Level of significance (LOS) given as α = .10
Step 5
Test statistics t = (x(bar) – value given in null hypothesis)/(s/n) =
Skip step 6
Step 7
x(bar) = 7785.47, s = 1002.18, n = 15
Test statistics t = (7785.47-8000)/(1002.18/15) = -0.83
Step 8
Since it’s a left tailed test, the p-value lies on the left side of the t-curve with 14 d. f.
p – value = area to the left of -0.83
we can not compute exact p-value as -0.83 or +0.83 are not listed in the table.
With approximation we can say that p-value >0 .1
Step 9
Decision: since p-value > given value of alpha (in step 4), we decide not to reject the null
null hypothesis at 10% LOS
Conclusion : and conclude that mean rate of uptake radio-labeled amino acid in all
bacteria cultures with nitrates is not less than 8000
Minitab output
Test of mu = 8000 vs < 8000
Variable
a
N
15
Mean
7785.47
StDev
1002.18
SE Mean
258.76
95%
Upper
Bound
8241.23
T
-0.83
P
0.210