In order to estimate the average GPA of students at a college, a professor takes a random sample of 57 students and find a sample mean of 2.79 with a sample standard deviation of 1.81. Write out the formula you should use and calculate the margin of error for a 95% confidence interval. (b) When conducting a new poll, what is the minimum sample size you would need to be 90% confident that the population proportion is estimated to within a 0.04 margin of error? Round your answer up to the nearest whole number.
(a) In order to estimate the average GPA of students at a college, a professor takes a random sample of 57 students and find a sample mean of 2.79 with a sample standard deviation of 1.81. Write out the formula you should use and calculate the margin of error for a 95% confidence interval.
(b) When conducting a new poll, what is the minimum sample size you would need to be 90% confident that the population proportion is estimated to within a 0.04 margin of error? Round your answer up to the nearest whole number.
Solution:
Note: Hello! As you have posted 2 different questions, we are answering the first question (a). In case you require the unanswered question also, kindly re-post them as separate question.
a.
Let X be the GPA of students at a college.
From the given information, x-bar=2.79. S=1.81 and n=57.
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