statistics test

MIAMI DADE COLLEGE: STA 2023 – Statistical Methods

Use the following distribution to answer questions 3 and 4.

1) What is the total area under the curve?

A) 1 B) 3 C) 2500 D) 3000

2) What is the mean?

A) 1 B) 3 C) 2500 D) 3000

Find the area under the standard normal distribution curve.

3) Between z = 0 and z = .75

A).07734 B) .7734 C) .2734 D) 27.34

4) To the left of z = -1.39

A) 8.23 B) .0082 C) .82 D) .0823

5) To the left of z = 1.23

A) .8907 B) .1093 C) .2266 D) 89.07

6) To the right of z = 1.23

A) .8907 B) .1093 C) .2266 D) 89.07

7) Between z = – 0.75 and z = 1.23

A) .8907 B) .1093 C) .2266 D) .6641

The average credit card debt for college seniors is $3262. If the debt is normally distributed with a standard deviation of $1100. Find these probabilities.

8) That the senior owes at least $1000

A).9803 B) 9.803 C) -2.06 D) .0206

9) That the senior owes more than $4000

A) .7486 B) .1486 C) .2514 D) 51.40

10) To qualify for a police academy, candidates must score in the top 10% on a general abilities test. The test has a mean of 200 and a standard deviation of 20. Find the lowest possible score to qualify. Assume the test scores are normally distributed.

A) 226 B) 1.28 C) 90% D) 200

The average credit card debt for college seniors is $3173. If the debt is normally distributed with a standard deviation of $1120. Find these probabilities.

11) What is the probability that a randomly selected undergraduate has a credit balance less than $2700?

A) -0.42 B) -2.11 C) .3372 D) .0174

12) You randomly select undergraduate. What is the probability that their mean balance less than $2700?

A) -0.42 B) -2.11 C) .3372 D) .0174

13) In a binomial experiment. N= 45, p = .47, and q = 0.53. Find the mean?

A) 21.15 B) 23.85 C) 3.35 D) 4.6

14) In a binomial experiment. N= 45, p = .47, and q = 0.53. Find the standard deviation?

A) 21.15 B) 23.85 C) 3.35 D) 4.6

15) In a recent study of 35 ninth-grade students, the mean number of hours per week that they played video games was 16.6. The standard deviation of the population was 2.8. Find the 95 % confidence interval of the mean of the time playing video games.

A) (157, 175) B) (15.7, 17.5) C) (-15.7, -17.5) D) (1.57, 1.75)

16) A scientist wishes to estimate the average depth of a river. He wants to be 99% confident that the estimate is accurate within 2 feet. From a previous study, the standard deviation of the depths measured was 4.33 feet. Find the Minimum Sample Size Needed for an Interval Estimate of the POPULATION MEAN

A) 21.2 B) 32 C) .32 D) 25

17) Ten randomly selected people were asked how long thy sept at night. The mean time was 7.1 hours, and the standard deviation was 0.78 hours. Find the 95% confidence interval of the meantime. Assume the variable is normally distributed

A) (157, 175) B) (15.7, 17.5) C) (65.4, 76.6) D) (6.54, 7.66)

18) A survey of 1500 adults found that 39% said that they would take more vacations this year than last year. Find the 95% confidence interval for the true proportion of adults who said that they will travel more this year.

A) – .365