Answer:
Step-by-step explanation:
Given that the random variable X is normally distributed, with
mean = 50 and standard deviation = 7.
Then we have z= 
Using this and normal table we find that
a) 
b) When z=0.02
we get

c) 90th percentile z value =1.645
90th percentile of X 
x = ×-3/4
because you hace the variable x and you do not know the number of fruit snacks he ate and you need to have the same variables to properly find the answer.
6%=0.06
28(0.06)
= 1.68 ---> tax
28+1.68
= 29.68
Jen and Sarah spent 29.68 dollars including tax
I hope this answer helped you and have a wonderful day!