MATH221 Quizzes W3 Homework

Sixty-eight percent of US adults have little confidence in their cars. You randomly select eleven US adults. Find the probability that the number of US adults who have little confidence in their cars is (1) exactly eight and then find the probability that it is (2) more than 6.

(1) 0.247 (2) 0.744

Sixty-one percent of employees make judgements about their co-workers based on the cleanliness of their desk. You randomly select 8 employees and ask them if they judge co-workers based on this criterion. The random variable is the number of employees who judge their co-workers by cleanliness. Which outcomes of this binomial distribution would be considered unusual?

0, 1, 2, 8

A survey found that 39% of all gamers play video games on their smartphones. Ten frequent gamers are randomly selected. The random variable represents the number of frequent games who play video games on their smartphones. What is the value of p?

0.39

Off the production line, there is a 3.7% chance that a candle is defective. If the company selected 45 candles off the line, what is the probability that fewer than 3 would be defective?

0.768

Consider the following table. Defects in batch 0.21, 0.37, 0.22, 010, 0.07, 0.03 Probability 2, 3, 4, 5, 6, 7 Find the standard deviation of this variable.

1.28

Consider the following table. Defects in batch 0.09, 0.24, 0.41, 0.12, 0.10, 0.04 Probability 0, 1, 2, 3, 4, 5 Find the variance of this variable.

1.48

The probability of a potential employee passing a drug test is 86%. If you selected 15 potential employees and gave them a drug test, how many would you expect to pass the test?

13 employees

Consider the following table. Age Group 18-29, 30-39, 40-49, 50-59, 60-69, 70 and over Frequency 9831, 7845, 6869, 6323, 5410, 5279

18.9%

Consider the following table. Weekly hours worked 1-30 (average=23), 31-40 (average=36), 41-50 (average=43), 51 and over (average=54) Probability 0.08, 0.10, 0.74, 0.08 Find the mean of this variable.

41.6

Thirty-five percent of teens buy soda (pop) at least once each week. Eleven kids are randomly selected. The random variable represents the number of these kids who purchase soda (pop) at least once each week. For this to be a binomial experiment, what assumption needs to be made?

All the kids eligible to be selected are teens

Let x represent the number of pets in pet stores. This would be considered what type of variable:

Discrete

Let x represent the number of players on a sports field. This would be considered what type of variable:

Discrete

A supplier must create metal rods that are 2.1 inches width to fit into the next step of production. Can a binomial experiment be used to determine the probability that the rods are too wide, too narrow, or about right?

No, as there are three possible outcomes, rather than two possible outcomes

Eight baseballs are randomly selected from the production line to see if their stitching is straight. Over time, the company has found that 93.8% of all their baseballs have straight stitching. If exactly six of the eight have straight stitching, should the company stop the production line?

No, the probability of exactly six have straight stitching is not unusual

In a box of 12 pens, there is one that does not work. Employees take pens as needed. The pens are not returned, once taken. You are the 5th employee to take a pen. Is this a binomial experiment?

No, the probability of getting the broken pen changes as there is no replacement