This is the correct answers
We are given with
x1 = 20 min
s1 = 2 min
x2 = 30 min
s2 = 4 min
p = 0.9
Condition (x > 25)
We need to get the t-value between the two means and comparing it wit the t-value for the time of 25 minutes given that there is a 90% probability that the weather will be good. Simply use the t-test formula and use the t-test table to get the probability.
Round off the decimals to a sensible number.
So 3.7 would be 4 and 10.2 would be 10.
In this case, it would be (2 × 4 + 8) × 10 which is 160.
