# Sampling distribution of the difference in sample proportions -Probability example | Summary and Q&A

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October 27, 2020
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Sampling distribution of the difference in sample proportions -Probability example

## TL;DR

Calculate the probability that the sample proportion of defects from Plant B is greater than the sample proportion from Plant A, which is approximately 21%.

## Questions & Answers

### Q: What is the main objective of the video?

The main objective of the video is to find the probability that the sample proportion of defects from Plant B is greater than the sample proportion from Plant A.

### Q: How is the problem of finding the probability transformed?

The problem is transformed by calculating the difference between the sample proportions, and then finding the probability of the difference being less than zero.

### Q: How is Z-value used in the calculation?

Z-value is used to determine how many standard deviations below the mean the given value is. In this case, it helps in calculating the Z-value for the difference between the sample proportions.

### Q: How is the Z-value lookup table used?

The Z-value lookup table is used to find the area under the normal curve up to and including a specific Z-value. In this case, it helps in finding the probability associated with a Z-value of -0.8.

## Summary & Key Takeaways

• The video discusses finding the probability of the sample proportion of defects from Plant B being greater than the sample proportion from Plant A.

• By calculating the difference in sample proportions, the problem is transformed to finding the probability of the difference being less than zero.

• To solve this, the video explains how to use Z-values and a Z lookup table.