# Urgent questions regarding q5 and q6 of the practice exam!

In question 5 we did not change the percentage to number. We used these numbers as it is.

7.99% - 2.26x2.46% = 2.44%

7.99% - 2.26*2.46% = 13.55%

However, in question 6 you change sample variances (0.82% and 0.93%) to (0.0082 and 0.0093). Therefore, we get Pooled variance of 0.0088 instead of 0.88.

Q 1. Why is it so? Could you please explain it? This was not explained in the videos, therefore I am too much confused at this point.

Then you used pooled variance of 0.05 in the calculation of standard error instead of 0.0088.

Q.2 Why? Where did 0.05 come from? How does the pooled variance change?

Q. 3. In this video https://learn.365datascience.com/courses/statistics/confidence-intervals-two-means-independent-samples-part2/ you explained that Pooled value is calculated based on sample sizes and sample standard deviations. However, in the solution of question 6, you use sample variance. How should I understand it? What did I miss?

I read other questions which some of which were similar, but you did not give answers to them. How can we continue education without understanding these points?