MAT 202 Random Variables Checkpoint 4
Color-blindness is any abnormality of the color vision system that causes a person to see colors differently than most people or to
have difficulty distinguishing among certain colors (www.visionrx.xom).
Color-blindness is gender-based, with the majority of sufferers being males.
Roughly 8% of white males have some form of color-blindness, while the incidence among white females is only 1%.
A random sample of 20 white males and 40 white females was chosen. Let X be the number of males (out of the
20) who are color-blind.
Let Y be the number of females (out of the 40) who are color-blind.
Let Z be the total number of color-blind individuals in the sample (males and females together).
Question 1 of 4 Points: 10
Which of the following is true regarding the random variables X and Y?
Both X and Y can be well-approximated by normal random variables. Only X can be well-approximated by a
normal random variable.
Only Y can be well-approximated by a normal random variable.
Neither X nor Y can be well-approximated by a normal random variable.
The remaining questions refer to the following information:
Suppose the scores on an exam are normally distributed with a mean μ = 75 points, and standard deviation σ = 8
points.
Question 2 of 4 Points: 10
The instructor wanted to "pass" anyone who scored above 69. What proportion of exams will have passing scores?
.25
.75
.2266
.7734
Color-blindness is any abnormality of the color vision system that causes a person to see colors differently than most people or to
have difficulty distinguishing among certain colors (www.visionrx.xom).
Color-blindness is gender-based, with the majority of sufferers being males.
Roughly 8% of white males have some form of color-blindness, while the incidence among white females is only 1%.
A random sample of 20 white males and 40 white females was chosen. Let X be the number of males (out of the
20) who are color-blind.
Let Y be the number of females (out of the 40) who are color-blind.
Let Z be the total number of color-blind individuals in the sample (males and females together).
Question 1 of 4 Points: 10
Which of the following is true regarding the random variables X and Y?
Both X and Y can be well-approximated by normal random variables. Only X can be well-approximated by a
normal random variable.
Only Y can be well-approximated by a normal random variable.
Neither X nor Y can be well-approximated by a normal random variable.
The remaining questions refer to the following information:
Suppose the scores on an exam are normally distributed with a mean μ = 75 points, and standard deviation σ = 8
points.
Question 2 of 4 Points: 10
The instructor wanted to "pass" anyone who scored above 69. What proportion of exams will have passing scores?
.25
.75
.2266
.7734
