Question

The number of defective units in a production run of 850 circuit boards are normally distributed with 21 defective units and 3 defective units. Find the probability P(17 < X < 25) with the help of the graphing calculator. Round your answer to the nearest integer.

77%

81%

80%

82%

Answer 1

82%

Explanation:

We let the random variable X denote the number of defective units in the production run. Therefore, X is normally distributed with a mean of 21 defective units and a standard deviation of 3 defective units.

We are required to find the probability, P(17 < X < 25), that the number of defective units in the production run is between 17 and 25.

This can be carried out easily in stat-crunch;

In stat crunch, click Stat then Calculators and select Normal

In the pop-up window that appears click Between

Input the value of the mean as 21 and that of the standard deviation as 3

Then input the values 17 and 25

click compute

Stat-Crunch returns a probability of approximately 82%

Find the attachment below.