The number of hours of sleep for college students is normally distributed with m

Question

The number of hours of sleep for college students is normally distributed with mean 7 hours and standard deviation 0.9 hours. Find the 78th percentile. (A) 7.73 hours (B) 7.69 hours (C) 6.31 hours (D) 6.27 hours

Currently, the mean miles per gallon for a certain model of car is 33. After making improvements, engineers found that for 15 cars, the average miles per gallon is 34.66 and the standard deviation is 4.9. Assume that the sample comes from a normal distribution. Find the p-value to test the claim that the mean miles per gallon has increased after making these improvements. (A) 0.2106 (B) 0.1053 (C) 0.8947 (D) 0.1580

A tourist in Europe plans to visit 10 different cities during a 2 week vacation. In how many ways can they visit 5 cities once during the first week? (A) 7,048 (B) 13,069 (C) 30,240 (D) 252

Explanation / Answer

z for 78% can be found using the normal distribution table as 0.77

thus the answer is mean+z*s=7+0.77*0.9=7.69 or option B

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