Unit 6 Math 4 Exam Review Probability Distributions

The 40 yards sprint times for a soccer team are found to be normally distributed with a mean of 5.2 seconds and a standard deviation of 0.3 seconds.  What is the z-score for a player who runs a time of 5.6 seconds?

• -1.33
• 1.33
• 0.88
• 1.02

The mean GPA of students in a course at UCDavis is 3.2 with a standard deviation of 0.3. What percent of students in the course have a GPA between  2.9 and 3.8? 

• 81.5%
• 47.5%
• 68%
• 95%

The z-score represents.....

• the amount of standard deviations a data value is above or below the mean.
• the percentile the data value is above or below the mean.
• the amount of standard deviations a data value is above or below the median.
• the percent the data value is above or below the mean.

The mean number of accidents a week at a company is 6.4 with a standard deviation of 1.5.  What proportion of weeks would you expect to have more than 7 accidents?

• 0.3446
• 0.2856
• 0.4
• 0.6554

A game consists of rolling a colored die with three blue sides, two red sides, and one white side. A roll of blue loses. A roll of red pays $3.00. A roll of white pays $5.00. The charge to play the game is $2.00. Would you play the game? Why or why not?

• E(x)= -$.17

  Students should play the game because the expected value is negative

• E(x)= $.32

  Students should play the game because the expected value is positive

• E(x)= $.32

  Students should not play the game because the expected value is positive

• E(x)= -$.17

  Students should not play the game because the expected value is negative.

On Test A Marsha scored a 98. The mean of test A was 92 with a standard deviation of 8. If the mean of test B is 250 with a standard deviation of 26, what score must Marsha earn to do equivalently well on both tests?

• 269.5

• 230.5

• 226

• 276

A time of 98 is three standard deviations above the mean and a time of 42 is one standard deviation below the mean. What is the mean of the distribution?

• 14

• 56

• 70

• 84

The table above is a p.d. for the number of siblings students in a certain class have.  What value of P(x=4) makes this a valid p.d.?

What is the expected value for the number of siblings for this class?

• 2.11

• 1

• 1.5

• 1.79

Is this a probability distribution?

• No, the sum of p(x) does not equal 1.

• Yes, all p(x) are between 0 and 1.

• No, all p(x) are not between 0 and 1.

• Yes, the sum p(x) is 1.