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.

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.

jaredstone4 · Answer

The formula to find a z-score is as follows:

$$z-score = \frac{ observed value - mean }{ standard deviation }$$

So, plug in your values for the observed popping time, mean popping time, and standard deviation, and you will have a z-score.