1-X is a normally distributed random variable with mean 50 and standard deviation 5. What is the probability that2X will be less than 110? (Hint: What is the new mean of 2X? What is the new variance and standard deviation of 2X?)

Group of answer choices

A-0.023

B-0.159

C-0.841

D-0.977

------------------------------------------------------------------

2-Where is the 10th percentile of the Z distribution?

Group of answer choices

(A). - 1.28

(B) 0.10

(C) 0.90

(D) 1.28

-----------------------------------------------------

3-If an observation has a z-score of -1.5, how many standard deviations is itabove or below the mean?

Group of answer choices

A- 1.5 standard deviations above the mean

B- 0.066 standard deviations below the mean

C- 1.5 standard deviations below the mean

D- 0.066 standard deviations above the mean

----------------------------------------------------------------

4- For a normally distributed variable X with mean 40 and standard deviation 10, what is the probability that X equals exactly 30? In notation, what is(=30)P(X=30)?

Group of answer choices

A- 0

B- 0.841

C- 0.159

D- 0.242

-----------------------------------------------------------

5- What is the probability that a normally distributed random variable X is greater than 85 if=X=75 and=X= 4? CHOOSE THE CLOSEST ANSWER.

Group of answer choices

A- 2.5

B- 0.994

C- 0.006

D- 1

----------------------------------------------------

6- The time to complete a standardized exam is approximately normal with a mean of 70 minutes and a standard deviation of 10 minutes. The percentage of the students which take longer than 80 minutes to complete the exam is 84.13%.

Group of answer choices

A- True

B- False

-------------------------------------------------------

7- The Normal distribution is an example of a _________________ Distribution.

Group of answer choices

A- Continuous

B- Discrete

C- Neither

---------------------------------------------------

8- If the Z-score is 1.96, and X has a normal distribution with mean 60 and standard deviation 6, what X-value corresponds to this Z-score?

Group of answer choices

A- 67.96

B- 48.24

C- 61.96

D- 71.76

----------------------------------------------------

9- The time (X) to complete a standardized exam is approximately normal with a mean of 70 minutesand standard deviation of 10 minutes. How much time should be given to complete the exam so that 80% of the students will complete the exam in the time given?

Group of answer choices

A- 74.8 minutes

B- 84.7 minutes

C- 78.4 minutes

D- 92.3 minutes

----------------------------------------------------------

10-

Suppose X has a normal distribution with mean 10 and standard deviation 2. In order for the Z-score to be equal to 0, then X must be equal to

Group of answer choices

A- 10

B- None of these choices are correct

C- 2

D- 0

-----------------------------------------------------------

11- For a normal distribution, the mean is equal to the median.

Group of answer choices

A- True

B- False

----------------------------------------------------------

12-Suppose X has a normal distribution with mean 80 and standard deviation 5. What is the 90th percentile of X?

Group of answer choices

A- 90

B- 0.90

C- 86.4

D- 73.6

------------------------------------------------------------

13- Suppose X has a normal distribution with mean 80 and standard deviation 5. How many standard deviations above or below the mean is 70?

Group of answer choices

A- None of the other choices is correct

B- 10 standard deviations below the mean

C- 2 standard deviations below the mean

D- 2 standard deviations above the mean

------------------------------------------------------------

14- Suppose X = exam score and X has a normal distribution with mean 80 and standard deviation 5. Bob scored at the 90th percentile. What is Bob's Z-value (aka Z-score)?

Group of answer choices

A- 1.28

B- 10%

C- 86.4

D- 2

----------------------------------------------------------

15-

The 80th percentile of the standard normal (Z) distribution is .84.

Group of answer choices

A- True

B- False

-------------------------------------------------------

16-

What is P(Z < 0)?

Group of answer choices

A- Need more information to tell

B- 0

C- some negative number

D- 0.50

--------------------------------------------------------------

17-Suppose X is normal with mean -10 and standard deviation 2. What is P(X > -8)?

Group of answer choices

A- 0

B- 0.16

C- -0.16

D- 0.84

E- -0.84

---------------------------------------------------------------------

18-

The normal PROBABILITY plot is supposed to show a straight line if your data have a normal distribution.

Group of answer choices

A- True

B- False

-------------------------------------------------------------------

19-

Suppose test scores have a normal distribution with mean 80 and standard deviation 5. What proportion of the scores do we expect to be between 75 and 85?

Group of answer choices

A- 34%

B- 68%

C- None of the other choices is correct

D- 10%

--------------------------------------------------------------------------

20-

If you know that Bob scored at the 70th percentile, and you know the mean and standard deviation of all the exams, then you can find Bob's actual score.

Group of answer choices

A- True

B- False