Construct a probability distribution. Find the mean of the probability distribution.

STA2023
EXAM 3-Part 2

1-) A study was conducted to determine the number of cell phones each household has. The data are shown here.

Number of cell phones 0 1 2 3 4
Frequency 2 30 48 13 7

Construct a probability distribution.
Find the mean of the probability distribution.

2-) If 60% of all women are employed outside the home, find the probability that in a sample of 20 women, exactly 15 are employed outside the home.

3-) The average height of a certain age group of people is 53 inches. The standard deviation is 4 inches. If the variable is normally distributed, find the probability that a selected individual’s height will be greater than 59 inches.

4-) An irate student complained that the cost of textbooks was too high. He randomly surveyed 36 other students and found that the mean amount of money spent for texts was $121.60. If the standard deviation of the population was $6.36, find the 90% confidence interval of the true mean.

5-) A recent study stated that if a person chewed gum, the average number of sticks of gum he or she chewed daily was 8. To test the claim, a researcher selected a random sample of 36 gum chewers and found the mean number of sticks of gum chewed per day was 9. The standard deviation of the population is 1. At , is the number of sticks of gum a person chews per day actually greater than 8? Show hypothesis, test statistic or P-value, and the decision about the claim.

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