Question

Men’s heights are normally distributed with a mean of 72 inches and a standard deviation of 3.1 inches. A social organization for short people has a requirement that men must be at most 66 inches tall. What percentages of men meet this requirement? Choose the correct answer:

A-2.62%

B-2.59%

C-2.56%

D-2.68%

Find the critical value of t for a sample size of 24 and a 95% confidence level. Choose the correct value from below:

A-2.096

B-2.064

C-2.046

D-2.069

Construct a confidence interval for the population mean using a t-distribution:

c = 99% m = 16.7 s = 3.2 n = 20. Choose from the intervals listed below.

A-(14.563, 18.474)

B-(14.664 18.736)

C-(14.653, 18.747)

D-(14.646, 18.763)

Assume that adults have IQ scores that are normally distributed, with a mean of 107 and a standard deviation of 15. Find the probability that a randomly selected individual has an IQ between 75 and 117. Choose the correct value:

A-0.7318

B-0.7155

C-0.7320

D-0.7167

In a survey, 376 out of 1,078 US adults said they drink at least 4 cups of coffee a day. Find a point estimate (P) for the population proportion of US adults who drink at least 4 cups of coffee a day, then construct a 99% confidence interval for the proportion of adults who drink at least 4 cups of coffee a day.

A-P=0.0374; (31.14%, 38.26%)

B-P=0.3488; (32.03%, 37.72%)

C-P=0.3488; (32.49%, 37.88%)

D-P=0.3488; (31.14%, 38.62%)

Your firm wants to investigate how much money the typical tourist will spend on their next visit to New York. How many tourists should be included in your sample if you want to be 90% confident that the sample mean is within $17 from the population mean? From previous studies, we know that the standard deviation is $70.

A-45

B-46

C-47

D-48

The mean rent of a 3-bedroom apartment in Orlando is $1200. You randomly select 12 apartments around town. The rents are normally distributed with a standard deviation of $300. What is the probability that the mean rent is more than $1100?

A-0.1827

B-0.8173

C-0.1251

D-0.8749

A study of women’s weights found that a randomly selected sample of 150 women had a mean weight of 147.3 lb. Assuming that the population standard deviation is 19.6 lb., construct a 95% confidence interval estimate of the mean weight of all women. Choose the correct interval from below:

A-(144.211, 150.389)

B-(140.611, 146.789)

C-(144.667, 149.933)

D-(144.163, 150.437)

A music industry researcher wants to estimate, with a 90% confidence level, the proportion of young urban people (ages 21 to 35 years) who go to at least 3 concerts a year. Previous studies show that 35% of those people (21 to 35 year olds) interviewed go to at least 3 concerts a year. The researcher wants to be accurate within 2% of the true proportion. Find the minimum sample size necessary.

A -2185

B-1539

C-2401

D-8740

Answer 1

1.Let X be the height of men

Then

To find P (X<66)

= P(z < -1.93)

= 0.0268 or 2.68% (from z table)

Answer is (D) 2.68%

2.

From t critical value table

critical value of t = 2.069

Answer is (D) 2.069

3. For 99% confidence with df = 20-1 =19

tc = 2.8609

99% confidence interval is

=

= (14.653 , 18.747)

Answer is (C) (14.653 , 18.747)

4.

Let X be the IQ score  

Then

To find P (75<X<117)

= P(-2.13<z < 0.67)

=0.7320 (from z table)

Answer is (C) 0.7320

5. P = 376/1078 =0.3488

For 99% confidence , zc =2.58

99% confidence interval for population proportion

= (0.3114 , 0.3862)

= (31.14% , 38.62%)

Answer is (D) (31.14% , 38.62%)

6.given margin of error =17

For 90% confidence , zc = 1.65

Answer is (B) 46

7.

.Let be the rent

Then

= P(z> -1.15)

= 0.8749 (from z table)

answer is (D) 0.8749

8. 95% confidence interval for mean

= (144.163 ,150.437)

Answer is (D) (144.163 ,150.437)

9.Margin of error = 0.02

Answer is (B) 1539