Question

DO NOT RESPOND UNLESS YOU INTEND TO ANSWER EACH QUESTION

1. A university dean is interested in determining the proportion of students who receive some sort of financial aid. Rather than examine the records for all students, the dean randomly selects 200 students and finds that 118 of them are receiving financial aid. The 95% confidence interval for p is 0.59 ± 0.07. Interpret this interval.

a. We are 95% confident that the true proportion of all students receiving financial aid is between 0.52 and 0.66.

b. 95% of the students get between 52% and 66% of their tuition paid for by financial aid.

c. We are 95% confident that between 52% and 66% of the sampled students receive some sort of financial aid.

d. We are 95% confident that 59% of the students are on some sort of financial aid.

2. A county clerk wants to estimate the proportion of voters who will need special election facilities. Suppose a sample of 400 voters was taken. If 150 need special election facilities, what is the upper confidence limit (UCL) for the 90% confidence interval for the population proportion of voters who will need special election facilities. Round your answer to 3 decimal places.

3. A confidence interval was used to estimate the proportion of statistics students who are females. A random sample of 72 statistics students generated the following 90% confidence interval: (0.438, 0.642). Based on the interval above, is the population proportion of females equal to 0.60?

a. No, and we are 90% sure of it.

b. No. The proportion is 54.17%

c. Yes, and we are 90% sure of it.

4. A hotel chain wants to estimate the mean number of rooms rented daily in a given month. The population of rooms rented daily is assumed to be normally distributed for each month with a standard deviation of 240 rooms. During February, a sample of 25 days has a sample mean of 370 rooms.

What is the upper confidence limit (UCL) of the 99% confidence interval for the mean number of rooms rented daily in a given month? Round your answer to the nearest whole number.

5. After an extensive advertising campaign, the manager of a company wants to estimate the proportion of potential customers that recognize a new product. She samples 120 potential consumers and finds that 54 recognize this product.

What type of confidence interval should the manager build?

a. A Z-based interval for the population mean.

b. A t-based interval for the population mean.

c. A Z-based interval for the population proportion.

6. As an aid to the establishment of personnel requirements, the director of a hospital wishes to estimate the mean number of people who are admitted to the emergency room during a 24-hour period. The director randomly selects 64 different 24-hour periods and determines the number of admissions for each. For the sample mean= 396 and s=100. What is the lower confidence limit (LCL) of the 95% confidence interval for the mean number of admissions per 24 hour period?

Answer 1