A bar is used to show subtraction in the case 4-3 (four take away three)
If the minute hand has turned 3/4 of the way around the face, it is equal to 45 minutes. (45/60)
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.
