Question

On a dry surface, the braking distances (in feet), from 60 miles per hour to a complete stop, of a sedan can be approximated by a normal distribution, as shown in the figure below. Use this information in Exercises 16-21 Braking Distance of a Sedan u 132 ft ơ-4.53 ft 115 120 125 130 135 140 145 Braking distance (in feet) 16. Find the braking distance of a sedan that corresponds to z2.75. 17. Find the braking distance of a sedan that corresponds to z-1.6. 18. What braking distance of a sedan represents the 90th percentile? 19. What braking distance of a sedan represents the first quartile? 20. What is the shortest braking distance of a sedan that can be in the top 15% of braking distances? 21. What is the longest braking distance of a sedan that can be in the bottom 20% of braking distances? In Exercises 22-23, find the indicated probabilities and interpret the results 22. Refer to Exercise 15. A random sample of 2 years is selected. Find the probability that the mean amount of black carbon emissions for the sample is (a) less than 12.3 gigagrams per year, (b) between 15.4 and 19.6 gigagrams per year, and (c) greater than 17.7 gigagrams per year Compare your answers with those in Exercise 15. 23. The mean ACT composite score in a recent year is 20.8. A random sample of 36 ACT composite scores is selected. What is the probability that the mean score for the sample is (a) less than 21.6, (b) more than 19.8, and (c) between 20.5 and 21.5? Assume ơ-5.6. (Source: ACT, Inc)

Answer 1

Note: To solve no 22. the data from exercise 15 about the mean, S.D and the sample size is needed. You can refer and see how no 23 is done it will be done in that way only after the required data is given.