Question

The popping times of the kernels in a certain brand of microwave popcorn are

normally distributed, with a mean of 150 seconds and a standard deviation of
13 seconds.
The first kernel pops 128 seconds after the microwave oven is started. What
is the z-score of this kernel? Round your answer to two decimal places.
O
O
O
O
A. -1.69
B. 0.59
c. -0.59
D. 1.69

Answer 1

The correct answer is A. -1.69

Explanation:

1. Let's review the information given to us to answer the question correctly:

Mean of the popping time of the kernels in a brand of microwave popcorn = 150 seconds

Standard deviation of the popping time of the kernels in a brand of microwave popcorn = 13 seconds

Time that first kernel pops = 128 seconds

2. What is the z-score of this kernel? Round your answer to two decimal places.

z-score = (Time that first kernel pops - Mean of the popping time)/Standard deviation of the popping time

Replacing with the real values, we have:

z-score = (128 - 150)/13

z-score = -22/13

z-score = - 1.69

The correct answer is A. -1.69