For some positive value of z, the probability that a standard normal variable is between 0 and z is 0.3770. What is the value of that z?
A) 0.18
B) 0.81
C) 1.16
D) 1.47

Question

Quizplus · Accepted Answer

Using a standard normal table, we can find the z-score that corresponds to a probability of 0.3770 being between 0 and z.
The closest probability we can find in the table is 0.3775, which corresponds to a z-score of 0.98. However, we want the probability to be slightly less than this, so we need to move to the left along the table.
The next closest probability we can find is 0.3767, which corresponds to a z-score of 1.15. Since we want to round to two decimal places, we can use 1.16 as our answer.
Therefore, the value of z is 1.16.

For Some Positive Value of Z, the Probability That a Standard