Miami Dade College STAT 2023 PROF: G. GARRIDO,Ph.D. TEST III Chapter 7 MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the quest 1) An economist is interested in studying the incomes of consumers in a particular country. 1) The population standard deviation is known to be $1,000. A random sample of 50 individuals resulted in a mean income of $15,000. What is the width of the 90% confidence interval? A) $364.30 B)$232.60 C) $465.23 D) $728.60 2) A university dean is interested in determining the proportion of students who receive some 2) 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. If the dean wanted to estimate the proportion of all students receiving financial aid to within 3% with 99% reliability, how many students would need to be sampled? A) n = 1,844 B)n = 1,435 C) n = 1,503 D) n = 1,784 Provide an appropriate response. 3) Find the critical value z corresponds to a 95% confidence level. c that A) 2.575 B)2.33 C) 1.645 3) D) 1.96 4) A random sample of 120 students has a test score average with a standard deviation of 9.2. 4) Find the margin of error if=0.98. c A) 0.18 B)1.96 C) 0.84 D) 0.82 5) Find the critical value, t c= 0.95 and = n 16. c, for A) 2.947 B)2.120 5) C) 2.131 D) 2.602 6) Find the value of E, the margin of error, for c = 0.95, n = 15 and s = 5.2. A) 2.96 B)0.74 C) 2.88 D) 2.36 6) 7) A survey of 100 fatal accidents showed that 12 were alcohol related. Find a point estimate 7) for p, the population proportion of accidents that were alcohol related. A) 0.88 B)0.12 C) 0.107 D) 0.136 8) A survey of 280 homeless persons showed that 63 were veterans. Construct a 90% confidence 8) interval for the proportion of homeless persons who are veterans. A) (0.167, 0.283) B)(0.161, 0.289) C) (0.176, 0.274) D) (0.184, 0.266) 9) A pollster wishes to estimate the proportion of United States voters who favor capital punishment. 9) How large a sample is needed in order to be 95% confident that the sample proportion will not differ from the true proportion by more than 5%? A) 271 B)769 C) 385 D) 10 GG//1 2 2 X R and XL , for c = 0.90 and n = 15. 10)Find the critical values, A) 4.075 and 31.319 C) 4.660 and 29.131 10) B)6.571 and 23.685 D) 5.629 and 26.119 Assume the sample is taken from a normally distributed population and construct the indicated confiden 11)A random sample of 20 women have a mean height of 62.5 inches and a standard deviation 11)of 3.2 2 inches. Construct a 98% confidence interval for the population variance, . A) (2.3, 5.0) B)(1.7, 8.0) C) (5.7, 26.8) D) (5.4, 25.5) Provide an appropriate response. 12)Construct a 90% confidence interval for the population mean, . Assume the population has 12) a normal distribution. A sample of 15 randomly selected students has a grade point average of 2.86 with a standard deviation of 0.78. A) (2.51, 3.21) B)(2.37, 3.56) C) (2.41, 3.42) D) (2.28, 3.66) 13)The standard IQ test has a mean of 101 and a standard deviation of 16. We want to be 98% 13)certain that we are within 4 IQ points of the true mean. Determine the required sample size. A) 10 B)1 C) 87 D) 188 SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question 14)A manufacturer receives an order for fluorescent light bulbs. The order requires that 14) the bulbs have a mean life span of 500 hours. The manufacturer selects a random sample of 25 fluorescent light bulbs and finds that they have a mean life span of 495 hours with a standard deviation of 15 hours. Test to see if the manufacturer is making acceptable light bulbs. Use a 95% confidence level. Assume the data are normally distributed. MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the quest 15)A researcher wishes to estimate the number of households with two cars. How large a sample 15) is needed in order to be 98% confident that the sample proportion will not differ from the true proportion by more than 5%? A previous study indicates that the proportion of households with two cars is 19%. A) 413 B)8 C) 237 D) 335 Assume the sample is taken from a normally distributed population and construct the indicated confiden - and- leaf plot shows the test scores of 16 randomly selected students. Construct 16) 16)The stem a 99% confidence interval for the population standard deviation. 5 6 7 8 9 9 583 74429 5835 317 A) (7.61, 20.33) B)(62.18, 363.63) C) (7.89, 19.07) 2 D) (57.97, 413.27) Keiser University Statistics 2023 Exam III -Chapter 6 (Version Diurno) Prof. Dr. Gredy Garrido Name___________________________________ MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. Using the following uniform density curve, answer the question. 1) What is the probability that the random variable has a value greater than 5? A) 0.325 B) 0.375 C) 0.250 D) 0.500 2) What is the probability that the random variable has a value less than 6? A) 0.750 B) 0.625 C) 0.875 D) 0.500 3) What is the probability that the random variable has a value greater than 1.3? A) 0.7875 B) 0.9625 C) 0.8375 D) 0.7125 4) What is the probability that the random variable has a value between 5.3 and 5.7? A) 0.1750 B) 0.0750 C) 0.3000 D) 0.0500 1) 2) 3) 4) Assume that the weight loss for the first month of a diet program varies between 6 pounds and 12 pounds, and is spread evenly over the range of possibilities, so that there is a uniform distribution. Find the probability of the given range of pounds lost. 5) More than 10 pounds 5) 5 1 1 2 A) B) C) D) 6 3 7 3 Find the area of the shaded region. The graph depicts the standard normal distribution with mean 0 and standard deviation 1. 6) 6) A) 0.7224 GG//1 B) 0.2224 C) 0.2190 D) 0.2776 stat 2023 Exam I 7) A) 0.8708 7) B) 0.8485 C) 0.8907 D) 0.1292 8) 8) A) 0.8212 B) 0.3576 C) 0.6424 D) 0.1788 Find the indicated z score. The graph depicts the standard normal distribution with mean 0 and standard deviation 1. 9) Shaded area is 0.4013. 9) A) 0.57 B) -0.25 C) -0.57 D) 0.25 10) Shaded area is 0.4483. A) 0.6736 10) B) 0.13 If z is a standard normal variable, find the probability. 11) The probability that z lies between -2.41 and 0 A) 0.5080 B) 0.4920 12) The probability that z lies between -1.10 and -0.36 A) 0.2237 B) -0.2237 13) P(z < 0.97) A) 0.8078 B) 0.8315 C) 0.3264 D) -0.13 C) 0.4910 D) 0.0948 C) 0.4951 D) 0.2239 C) 0.1660 2 D) 0.8340 11) 12) 13) stat 2023 Exam I Solve the problem. Round to the nearest tenth unless indicated otherwise. 14) In one region, the September energy consumption levels for single-family homes are found to be normally distributed with a mean of 1050 kWh and a standard deviation of 218 kWh. Find P45, which is the consumption level separating the bottom 45% from the top 55%. A) 1078.3 B) 1087.8 C) 1148.1 14) D) 1021.7 Solve the problem. 15) The amount of snowfall falling in a certain mountain range is normally distributed with a mean of 70 inches, and a standard deviation of 10 inches. What is the probability that the mean annual snowfall during 25 randomly picked years will exceed 72.8 inches? A) 0.4192 B) 0.0808 C) 0.5808 D) 0.0026 15) 16) A bank's loan officer rates applicants for credit. The ratings are normally distributed with a mean of 200 and a standard deviation of 50. If 40 different applicants are randomly selected, find the probability that their mean is above 215. A) 0.0287 B) 0.1179 C) 0.3821 D) 0.4713 16) 17) For women aged 18-24, systolic blood pressures (in mm Hg) are normally distributed with a mean of 114.8 and a standard deviation of 13.1. If 23 women aged 18-24 are randomly selected, find the probability that their mean systolic blood pressure is between 119 and 122. A) 0.9341 B) 0.0833 C) 0.0577 D) 0.3343 17) 18) Suppose that replacement times for washing machines are normally distributed with a mean of 9.3 years and a standard deviation of 1.1 years. Find the probability that 70 randomly selected washing machines will have a mean replacement time less than 9.1 years. A) 0.4357 B) 0.0643 C) 0.0714 D) 0.4286 18) 19) A study of the amount of time it takes a mechanic to rebuild the transmission for a 2005 Chevrolet Cavalier shows that the mean is 8.4 hours and the standard deviation is 1.8 hours. If 40 mechanics are randomly selected, find the probability that their mean rebuild time exceeds 8.7 hours. A) 0.1946 B) 0.1285 C) 0.1346 D) 0.1469 19) 20) A study of the amount of time it takes a mechanic to rebuild the transmission for a 2005 Chevrolet Cavalier shows that the mean is 8.4 hours and the standard deviation is 1.8 hours. If 40 mechanics are randomly selected, find the probability that their mean rebuild time exceeds 9.1 hours. A) 0.0046 B) 0.1046 C) 0.1285 D) 0.0069 20) 3 Answer Key Testname: UNTITLED2 1) 2) 3) 4) 5) 6) 7) 8) 9) 10) 11) 12) 13) 14) 15) 16) 17) 18) 19) 20) B A C D B D A C B B B A D D B A C B D D 4