Random Variables

A random variable is a(n) _______________ that describes a random occurrence.

• numerical value

• outcome

• Event

• probability

• .88

• .12

• .78

• .22

• .21

• .79

• .64

• .89

The mean amount of time to make the batter for a cake is 14 minutes with a standard deviation of 2.5 minutes. The mean amount of time to bake the cake is 35 minutes with a standard deviation of 6.2 minutes. What is the mean time to make and bake a cake? What is the standard deviation?

• mean = 49 min sd = 8.7 min

• mean = 49 min sd = 6.685 min

• mean = 49 min sd = 44.69 min

• mean = 21 min sd = 8.7 min

The mean hourly salary for a high school graduate (H) is $13.50 per hour with a standard deviation of $5.75. The mean hourly salary for a person with an Associate's degree A) is $19.75 with a standard deviation of $9.25. What is the standard deviation of the difference in the hourly salaries between a high school graduate and a person who earned an Associate's degree? D = H - A.

• $10.89

• $118.63

• $-3.50

• $12.20

The mean hourly salary for a high school graduate (H) is $13.50 per hour with a standard deviation of $5.75. The mean hourly salary for a person with an Associate's degree (A)is $19.75 with a standard deviation of $9.25. What is expected difference in the hourly salaries between a high school graduate and a person who earned an Associate's degree? D = H - A.

• $33.25

• $-3.50

• $-6.25

• $15.00

State whether the variable is Discrete or Continuous;

A film critic's rating of a film, 0 to 4 stars

• Discrete

• Continuous

State whether the variable is Discrete or Continuous;

The speed of a car

• Discrete

• Continuous

A company states that 2% of its computers are returned for defects. We take a sample of 100 computers to find the probability of 10 being defective. Is this a binomial distribution?

• No because there is not a fixed number of trials.

• No because there are more than 2 outcomes.

• Yes since there are a fixed number of independent trials, outcomes in 2 categories, and the probability of defect is constant.

• No since computers would not be independent.

If 1.5% of the bolts made by an automotive factory are defective, what is the probability that in a shipment of 200 bolts, there are 6 defective bolts?

• binompdf(200, 0.015, 6) = 0.050

• binomcdf(200, 0.015, 5) = 0.9176

• binomcdf(200, 0.015, 6) = 0.9676

• geometpdf(0.015, 6) = 0.0137