Study and analyze each case. Apply the formula necessary to solve the stated problem.

CASE 1:

A random sample of size 70 has a standard deviation of 3.12. Assuming that there is a 92% confidence level, what is the margin of error?

CASE 2:

In a sample of 100 cars with a standard deviation of 25^km/_h speed. Find the margin of error if the level of confidence is 90%.

CASE 3:

Mr. V wanted to know the average weight (in kilos) of students in LAO University. He took arandom sample of 300 students and discovered that their average weight 55kg with a standard deviation of 0.8kg. Construct a 95% confidence interval for the mean weight of students in the University.

CASE 4:

The average price of a 50 cellphones is 13,500 with a sample standard deviation of 750. Find the 98% confidence interval of the true average price of the cellphones.

CASE 5:

Compute for the sample size needed if the margin of error is 15, with sample standard deviation of 43 and a 98% level of confidence.

CASE 6:

Yeshua wants to have a sample size of the number of children that he needs for his survey project. If he used a 99% confidence interval and a margin of error of 135.8 with a standard deviation of 400, find the sample size he needs