Question

Refer to the description of Problem 1 in the exam document (Frozen Spoon Ice-cream). When she looked at the data collected, Maria found a sample mean of 2.8 oz. It is known that the distribution of the amount of ice cream it takes for all Maria's customers to get a brain freeze is symmetric, unimodal, and has a standard deviation of 1.6 oz. Maria wants to compute a 98% confidence interval for the mean amount of ice cream it takes her customers to get a brain freeze. Fill in the following blanks with the corresponding correct values. Report all your answers as a number (no symbols) and round to two decimal places. Note that answers not following these exact specifications will receive no credit. 1. critical value for the interval above equals Report the positive value here. 2. standard error for the sample mean amount of ice cream it takes Maria's customers to get a brain freeze is 3. sample mean for the sample of customers selected by Maria

sample size. n = 49

Answer 1

Answer)

As the population s.d is known we can use standard normal z table to estimate the answers

A)

First we need to find the area in each tail

= (100-98)/2 = 1%

From z table, P(z<-2.33) = P(z>2.33) = 1%

So, critical.value is 2.33

2)

Standard error = s.d/√n = 1.6/√49 = 0.22857142857 = 0.23

C)

Sample mean = 2.8