Question

Suppose that the IQ’s of School A's students can be described by a Normal model with a mean of 130 and a standard deviation of 8 points. Also suppose that the IQ’s of students from School B can be described by a Normal model with mean of 120 and standard deviation of 10 points. We select 1 student at random from School A. Find the probability that this student’s IQ is at least 125 points.

Suppose that the IQ’s of School A students can be described by a Normal model with a mean of 130 and a standard deviation of 8 points. Also suppose that the IQ’s of students from School B can be described by a Normal model with mean of 120 and standard deviation of 10 points. We select 3 School B students at random. Find the probability that this group’s average IQ is at least 125 points.

School B admits 1,632 freshmen one year, and four years later 1,388 of them graduate on time. Now, they want to estimate the percentage of all their freshman enrollees who graduate on time. Create a 95% confidence interval and interpret your confidence interval. This is the upper limit:

School B admits 1,632 freshmen one year, and four years later 1,388 of them graduate on time. Now, they want to estimate the percentage of all their freshman enrollees who graduate on time. Create a 95% confidence interval and interpret your confidence interval. This is the lower limit:

School B admits 1,632 freshmen one year, and four years later 1,388 of them graduate on time. Now, they want to estimate the percentage of all their freshman enrollees who graduate on time. We want to reduce our margin of error by one half. Now how many freshmen must enter in one year for this to happen?

School B admits 1,632 freshmen one year, and four years later 1,388 of them graduate on time. Now, they want to estimate the percentage of all their freshman enrollees who graduate on time. One forgetful statistician obtained a margin of error equal to .012. The forgetful statistician then forgot which confidence level he used. Help the statistician by finding the confidence level he used to create his interval. Note: this is not an ordinary confidence level. Enter the value as a probability. (e.g. 95% = 0.95)

Answer 1

Dear student, we can provide you with the solution of 4 sub question at a time.

e) Here the population proportion of the graduate is not given so we will use the sample estimate

p=0.8505

ME=0.0087

sample size of 6454 is required