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Quiz 5

Question 1

Think about a density curve that consists of two line segments. The first goes from the point (0, 1) to the point (0.7, 1). The second goes from (0.7, 1) to (0.9, 2) in the xy-plane. What percent of observations fall below 0.10?

a) 0.90

b) 0.45

c) 0.10

d) 1.00

e) 0.05

f) None of the above

Question 2

Think about a density curve that consists of two line segments. The first goes from the point (0, 1) to the point (0.7, 1). The second goes from (0.7, 1) to (0.9, 2) in the xy-plane. What percent of observations fall between 0.7 and 0.9?

a) 0.20

b) 1.00

c) 0.05

d) 0.30

e) 0.50

f) None of the above Question 3 Consider a uniform density curve defined from x = 0 to x = 6. What percent of observations fall below 4?

a) 0.67

b) 0.40

c) 0.79



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d) 0.17

e) 0.25

f) None of the above Question 4 Consider a uniform density curve defined from x = 0 to x = 5. What percent of observations fall between 1 and 4?

a) 0.25 b) 0.20 c) 0.72 d) 0.80 e) 0.60 f) None of the above Question 5 Consider a spinner that, after a spin, will point to a number between zero and 1 with "uniform probability". Determine the probability: P(1/6 X 19/42).

a) 0.45 b) 1.00 c) 0.71 d) 0.29 e) 0.17 f) None of the above Question 6 The heights of students in a class are normally distributed with mean 54 inches and standard deviation 6 inches. Use the Empirical Rule to determine the interval that contains the middle 99.7% of the heights.

a) [42, 66] b) [36, 72]



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c) [48, 66]

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d) [33, 75]

e) [48, 60]

f) None of the above

Question 7

The length of time needed to complete a certain test is normally distributed with mean 74 minutes and standard deviation 12 minutes. Find the probability that it will take less than 88 minutes to complete the test.

a) 0.4392

b) 0.8783

c) 0.5608

d) 0.1217

e) 0.5000

f) None of the above Question 8 If X is normally distributed with a mean of 20 and a standard deviation of 2, find P(20 X 22).

a) 0.541

b) 0.641

c) 0.841

d) 0.741

e) 0.341

f) None of the above

Question 9

Suppose that X is normally distributed with a mean of 20 and a standard deviation of 18. What is P(X 62.48)?

a) 0.991

b) 0.012



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c) 0.491

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d) 0.009

e) 0.014

f) None of the above Question 10 Suppose that x is normally distributed with a mean of 10 and a standard deviation of 2. What is P(x 14.90)?

a) 0.493

b) 0.993

c) 0.007

d) 0.496

e) 0.994

f) None of the above

Question 11

Suppose that x is normally distributed with a mean of 50 and a standard deviation of 9. What is P(33.53 x 70.97)?

a) 0.495

b) 0.466

c) 0.490

d) 0.956

e) 0.471

f) None of the above

Question 12

At a college the scores on the chemistry final exam are approximately normally distributed, with a mean of 74 and a standard deviation of 9. The scores on the calculus final are also approximately normally distributed, with a mean of 82 and a standard deviation of 14. A student scored 79 on the chemistry final and 83 on the calculus final. Relative to the students in each respective class, in which subject did the student do better?

a) The student did equally well in each course



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b) Chemistry c) Calculus d) There is no basis for comparison e) None of the above Question 13 Find a value of c so that P(Z c) = 0.47. a) 1.08 b) 0.42 c) -0.08 d) 0.08 e) 0.92 f) None of the above

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Quiz 6

Question 1 Suppose that x is normally distributed with a mean of 50 and a standard deviation of 15. What is P(34.55 x 72.95)? a) 0.348 b) 0.785 c) 0.442 d) 0.353 e) 0.437 f) None of the above Question 2 Find a value of c so that P(Z c) = 0.43. a) 0.35 b) 0.18 c) 0.02 d) -0.18 e) 0.82 f) None of the above Question 3 Suppose that x is normally distributed with a mean of 20 and a standard deviation of 15. What is P(-7.45 x 54.95)? a) 0.956 b) 0.490 c) 0.468



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d) 0.495

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e) 0.466

f) None of the above

Question 4

The length of time needed to complete a certain test is normally distributed with mean 95 minutes and standard deviation 10 minutes. Find the probability that it will take between 93 and 98 minutes to complete the test.

a) 0.1972

b) 0.8028

c) 0.5000

d) 0.0986

e) 0.4207

f) None of the above

Question 5

The length of time needed to complete a certain test is normally distributed with mean 74 minutes and standard deviation 17 minutes. Find the probability that it will take more than 70 minutes to complete the test.

a) 0.7035

b) 0.5000

c) 0.4070

d) 0.5930

e) 0.2965

f) None of the above Question 6 Which of the following statements is not true?

a) The sampling distribution of sample mean is approximately normal, mound-shaped, and symmetric for n > 30 or n = 30.



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b) The expected value of the sample mean, X, is always the same as the expected value of X, the distribution of the population from which the sample was taken.

c) The sampling distribution of the sample mean, X, is always reasonably like the distribution of X, the distribution from which the sample is taken.

d) The larger the sample size, the better will be the normal approximation to the sampling distribution of sample mean.

e) The standard deviation of the sampling distribution X of sample mean = /n where is the standard deviation of X.

f) None of the above

Question 7

Suppose a random sample of 80 measurements is selected from a population with a mean of 65 and a variance of 300. Select the pair that is the mean and standard error of x.

a) [65, 2.036]

b) [80, 2.136]

c) [65, 2.436]

d) [65, 2.236]

e) [65, 1.936]

f) None of the above

Question 8

A random sample of 1225 16-ounce cans of fruit nectar is drawn from among all cans produced in a run. Prior experience has shown that the distribution of the contents has a mean of 16 ounces and a standard deviation of 0.16 ounce. What is the probability that the mean contents of the 1225 sample cans is less than 15.992 ounces?

a) 0.070

b) 0.090

c) 0.060

d) 0.080

e) 0.040

f) None of the above



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