STEP - BY - STEP EXPLANATION
What to find?
Percentage of population that has a bill less than $87
Given:
mean (μ)= 70
standard deviation (σ) =8
score (x) =87
Step 1
Recall the formula to use.

Step 2
Substitute the values into the above.

Step 3
Use table to find the value.

Step 4
Convert to percentage.

ANSWER
D) 98 %