1.A company makes 20,000 laptops each year. Most of these laptops perform well f

Question

1.A company makes 20,000 laptops each year. Most of these laptops perform well for several years but eventually, all of these laptops stop working. The company knows that the laptops last for an average of 38 months, with a standard deviation of 6 months. The company offers a 36-month warranty. If laptop life is normally distributed, the percentage of laptops that will stop working before the warranty expires is about____________. Suppose that the company has 200 salespeople who sell the laptops; each sells 9 laptops. For each salesperson, you calculate the mean time before the laptop stops working. The percentage of salespeople who have mean below 36 months is __________.

a. 37%; 16%

b. 37%; 0%

c. 63%; 2%

d. 63%; 98%

e. 70%; 98%

f. 63%; 0%

2. At summer soccer camp, 320 children do push-ups for one minute each morning. You know that the number of push-ups they do is normally distributed with a mean of 12 and a standard deviation of 4. The percentage of children who do more than 14 push-ups is ____________. Suppose you randomly assign children to 20 teams that have 16 players each. For each team, you obtain the mean number of push-ups. The percentage of means that are more than 14 is about __________.

a. 14%; 2%

b. 31%; 2%

c. 69%; 4%

d. 14%; 0%

e. 69%; 2%

f. 31%; 0%

3. If the parent population has a mean of 75 and standard deviation of 5, then the distribution of the means will have a mean that is

a. less than 75

b. less than 5

c. equal to 75

d. equal to 5

e. more than 75

f. more than 5

4. If the parent population is bimodal, the distribution of the means (assuming a large sample size) is likely to be

a. negatively skewed

b. positively skewed

c. unimodal

d. even more strongly bimodal

Explanation / Answer

Q-1

Part-b

Q-2

Part-f

Q-3

Part-c

Q-4

Part-c

This is due to central llimti theoremt

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