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.