Quiz 6.4
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Part 1 of 1 - Quiz 6.4 9.0/ 10.0 Points
Question 1 of 10 1.0/ 1.0 Points
Let X ~ N(12, 2.2). If Y = 3.5X + 4.1, what is the standard deviation of Y, rounded to three
decimal places?  
Question 2 of 10 1.0/ 1.0 Points
Let Y ~ N(72, 14). Calculate Pr(69 < Y < 75). Round your answer to two decimal places Question 3 of 10 0.0/ 1.0 Points
Suppose the I.Q. of a certain population follows a Normal distribution with a mean of 100 and a
variance of 36. If you select a random person from this population, what is the probability that
his/her I.Q. will be between 105 and 111? Round your answer to two decimal places. 0.76
Question 4 of 10 1.0/ 1.0 Points
If X ~ N( , ), find Pr( - < X < + 2 ). Round your answer to three decimal
places. 0.819
Question 5 of 10 1.0/ 1.0 Points

Find , the 20% point of the Standard Normal distribution

Question 6 of 10 1.0/ 1.0 Points
If X ~ N( , ), find Pr( - 0.5 < X < + 0.5 ). Round your answer to three decimal
places.
Question 7 of 10 1.0/ 1.0 Points
If X ~ N( , ), find Pr(X < - 2.3 ). Round your answer to three decimal places.
Question 8 of 10 1.0/ 1.0 Points
Let Y ~ N(125, 16). Calculate Pr(Y < 130). Round your answer to two decimal places
Question 9 of 10 1.0/ 1.0 Points
Consider two independent Normal random variables: X ~ N(132, ) and Y ~ N(123, ).
What is the distribution of W = X + Y?
A. W ~ N(9, 49)
B. W ~ N(255, 49)
C. W ~ N(9, 29)
D. W ~ N(255, 29)
E. W ~ N(255, 7)
Question 10 of 10 1.0/ 1.0 Points
Suppose the I.Q. of a certain population follows a Normal distribution with a mean of 101 and a
standard deviation of 8.5. If you select a random person from this population, what is the
probability that his/her I.Q. will be less than 98? Round your answer to two decimal places. 0.36
Quiz 6.4
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Part 1 of 1 - Quiz 6.4 8.0/ 10.0 Points
Question 1 of 10 1.0/ 1.0 Points
Let Y ~ N(250, 28). Calculate Pr(Y > 242). Round your answer to two decimal places.
Question 2 of 10 1.0/ 1.0 Points
If X ~ N( , ), find Pr( - 0.5 < X < + 0.5 ). Round your answer to three decimal
places.
Question 3 of 10 0.0/ 1.0 Points
Suppose the I.Q. of a certain population follows a Normal distribution with a mean of 100 and a
variance of 36. If you select a random person from this population, what is the probability that
his/her I.Q. will be between 105 and 111? Round your answer to two decimal places. 0.59
Question 4 of 10 1.0/ 1.0 Points
Let X ~ N(12, 2.2). If Y = 3.5X + 4.1, what is the standard deviation of Y, rounded to three


decimal places?
Question 5 of 10 1.0/ 1.0 Points
Consider two independent Normal random variables: X ~ N(45, 9) and Y ~ N(54, 16). What is
the distribution of W = X - Y?
A. W ~ N(9, 25)
B. W ~ N(-9, 49)
C. W ~ N(-9, 7)
D. W ~ N(9, 7)
E. W ~ N(-9, 25)
Question 6 of 10 1.0/ 1.0 Points
If X ~ N( , ), find Pr( - < X < + 2 ). Round your answer to three decimal
places.
Question 7 of 10 1.0/ 1.0 Points
Suppose the I.Q. of a certain population follows a Normal distribution with a mean of 101 and a
standard deviation of 8.5. If you select a random person from this population, what is the
probability that his/her I.Q. will be less than 98? Round your answer to two decimal places. 0.36
Question 8 of 10 0.0/ 1.0 Points
If X ~ N( , ), find Pr(X < - 2.3 ). Round your answer to three decimal places.
Question 9 of 10 1.0/ 1.0 Points


Suppose the height of UCT students follows a Normal distribution with mean 1.57m and
variance 0.37m. If every student wore 8cm high heels, the new distribution of height would be:
A. N(1.57, 0.37)
B. N(1.65, 0.0296)
C. N(1.65, 0.45)
D. N(1.65, 0.37)
E. N(9.57, 0.37)
Question 10 of 10 1.0/ 1.0 Points
Consider two independent Normal random variables: X ~ N(132, ) and Y ~ N(123, ).
What is the distribution of W = X + Y?
A. W ~ N(9, 49)
B. W ~ N(255, 49)
C. W ~ N(9, 29)
D. W ~ N(255, 29)
E. W ~ N(255, 7)
Quiz 6.4
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Part 1 of 1 - Quiz 6.4 7.0/ 10.0 Points
Question 1 of 10 0.0/ 1.0 Points
Let Y ~ N(72, 14). Calculate Pr(69 < Y < 75). Round your answer to two decimal places. 0.03


Question 2 of 10 1.0/ 1.0 Points
Suppose the I.Q. of a certain population follows a Normal distribution with a mean of 101 and a
standard deviation of 8.5. If you select a random person from this population, what is the
probability that his/her I.Q. will be less than 98? Round your answer to two decimal places. 0.36
Question 3 of 10 0.0/ 1.0 Points
Suppose the I.Q. of a certain population follows a Normal distribution with a mean of 100 and a
variance of 36. If you select a random person from this population, what is the probability that
his/her I.Q. will be between 105 and 111? Round your answer to two decimal places. 0.76
Question 4 of 10 0.0/ 1.0 Points
Suppose the height of UCT students follows a Normal distribution with mean 1.57m and
variance 0.37m. If every student wore 8cm high heels, the new distribution of height would be:
A. N(1.57, 0.37)
B. N(1.65, 0.0296)
C. N(1.65, 0.45)
D. N(1.65, 0.37)
E. N(9.57, 0.37)
Question 5 of 10 1.0/ 1.0 Points
Find , the 20% point of the Standard Normal distribution. 0.84
Question 6 of 10 1.0/ 1.0 Points
If X ~ N( , ), find Pr( - < X < + 2 ). Round your answer to three decimal
places. 0.819


Question 7 of 10 1.0/ 1.0 Points
Consider two independent Normal random variables: X ~ N(132, ) and Y ~ N(123, ).
What is the distribution of W = X + Y?
A. W ~ N(9, 49)
B. W ~ N(255, 49)
C. W ~ N(9, 29)
D. W ~ N(255, 29)
E. W ~ N(255, 7)
Question 8 of 10 1.0/ 1.0 Points
Suppose the I.Q. of a certain population follows a Normal distribution with a mean of 92 and a
standard deviation of 10.5. If you select a random person from this population, what is the
probability that his/her I.Q. will be at least 100? Round your answer to two decimal places. 0.22
Question 9 of 10 1.0/ 1.0 Points
Consider two independent Normal random variables: X ~ N(45, 9) and Y ~ N(54, 16). What is
the distribution of W = X - Y?
A. W ~ N(9, 25)
B. W ~ N(-9, 49)
C. W ~ N(-9, 7)
D. W ~ N(9, 7)
E. W ~ N(-9, 25)
Question 10 of 10 1.0/ 1.0 Points
Let X ~ N(12, 2.2). If Y = 3.5X + 4.1, what is the standard deviation of Y, rounded to three
decimal places? 5.191