Question 1026014
z=(x-mean)/sd
so (5.86-9.6)/2=3.742=-1.87
(12.72-9.6)/2=3.12/2=1.56
we need the probability of -1.87 is less than z which is less than 1.56
That is 0.9099.
It makes sense because it is almost the difference between +/- 2 SD, which is 0.9544.