Unit 6 Random Variables Review

Cool TV game show
Players win prizes with probabilities shown:
P($0) = .70
P($500) = .25
P($5,000) = .05
What are the mean and the standard deviation of the prize variable?

• Mu = $375; sigma = $361
• Mu = $375; sigma = $1,083
• Mu = $1,833; sigma = $1,816
• Inadequate info is provided.

State whether it is Discrete or Continuous;

The temperature of metal as it cools

• Discrete

• Continuous

Tags

CCSS.HSF-LE.A.1B

State whether it is Discrete or Continuous;

The number of cars passing the school over a 10 - minute period

• Discrete

• Continuous

Tags

CCSS.HSF-LE.A.1B

The mean amount of time to mix 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 = 21 min sd = 8.7 min

• mean = 21 min sd = 6.685 min

Tags

CCSS.HSS.ID.A.2

CCSS.HSS.MD.A.2

A random variable X has a mean of 5 and a st. dev of 0.40. A random variable Y has a mean of 8 and a st. dev of 0.60. If both are independent, what is the st. dev of X - Y?

• 0.52
• 0.72
• 1.0
• Not here

Tags

CCSS.HSS.CP.A.2

A marketing survey compiled data on the number of cars in households.  If X = the number of cars, and we omit the rare cases of more than 5 cars, then X has the following probability distribution: 
X         0         1         2       3         4        5 
P(X)  0.24  0.37  0.20  0.11  0.05  0.03
What is the probability that a randomly chosen household has at least two cars?

• 0.20
• 0.29
• 0.39
• 0.61

Tags

CCSS.HSS.CP.A.1

CCSS.HSS.MD.A.1

CCSS.HSS.MD.A.3

If the height of a randomly selected woman is normally distributed with mean of 64.5 in and st. dev of 2.5 in, what proportion of women are between 65 and 67 inches?

• 0.14
• 0.16
• Not here
• 0.58

Tags

CCSS.HSS.ID.A.4

The American Red Cross says that about 11% of the U.S. population has Type B blood. A blood drive is being held at your school. What is the probability that the tenth blood donor is the first donor with Type B blood?

• approximately 0.00
• 0.316
• 0.0385 
• 0.279

The American Red Cross says that about 11% of the U.S. population has Type B blood. A blood drive is being held at your school.What is the probability that exactly 2 of the first 20 blood donors have Type B blood? 

• 0.316
• 0.282
• 0.001
• Not here

Tags

CCSS.HSS.CP.B.9

CCSS.HSS.MD.A.3

The American Red Cross says that about 11% of the U.S. population has Type B blood. A blood drive is being held at your school. What is the probability that at least 2 of the first 10 blood donors has Type B blood? 

• 0.088
• 0.697
• 0.214
• 0.303 

Tags

CCSS.HSS.CP.B.9

CCSS.HSS.MD.A.3