To solve this problem, we make use of the t statistic. So what we have to do is to calculate for the t score in this case and using the standard distribution tables, we locate for the p value using the t score value.
The formula for t score is given as:
t = (x – μ) / (σ / sqrt(n))
Where,
x = statistical mean of the sample = 40
n=number of individuals in the sample = 16
s=standard deviation = 20
μ=Population Mean = 30
Substituting the given values:
t = (40 – 30) / (20 / sqrt 16)
t = 10 / 5
t = 2
Using the standard distribution tables at degrees of freedom = n – 1 = 15, the value of p to the right is:
p = 0.032