Download Midterm 1, Version 1

C22.0103.05
MIDTERM 1
Name:________________________
This is the answer sheet. Circle the choice which best answers each question on
the exam. Do not write anything else on this sheet (besides your name and the
circles). When you are finished, hand in just this answer sheet. You can keep the
question sheets. There are 15 questions, each worth 5 points. Everyone receives
25 points for free. Good Luck!
1) (A) (B) (C) (D) (E)
11) (A) (B) (C) (D) (E)
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C22.0103
MIDTERM 1
1) The sample mean of the data set {6,4,2,6,7} is:
A) 6.25 B) 5 C) 6 D) 6.5 E) None of the Above.
2) The sample median of the data set {6,4,2,6,7} is:
A) 6.5 B) 2 C) 4 D) 6 E) None of the Above.
3) The range of the data set {6,4,2,6,7} is:
A) 2 B) 5 C) 0 D) 5 E) None of the Above.
4) Suppose that for a data set with n=3 observations, the sample mean is 6, the
sample median is 4, and the smallest observation is 2. Then the sample
standard deviation (to three significant figures) is:
A) 6.96 B) 6.24 C) 4.32 D) 5.29 E) None of the Above.
5) Suppose we have a data set of size n=10 and not all values are the same.
Suppose also that the sample mean is zero. If we double each number in the
data set, then:
A) The sample mean will change but the sample standard deviation will
not change.
B) The sample standard deviation will change but the sample mean will
not change.
C) Both the sample mean and sample standard deviation will change.
D) Neither the sample mean nor the sample standard deviation will
change.
E) It cannot be determined from the given information.
6) For a data set with n = 10 observations, if the interquartile range is zero then:
A) The sample standard deviation must be zero.
B) The sample standard deviation may or may not be zero.
C) The sample standard deviation cannot be zero.
7) In a certain county in New York, the mean family income is $200,000 and the
standard deviation is $50,000. The z-score for a family with income $300,000
is:
A) 100,000 B) −2 C) 2 D) 0 E) None of the Above.
8) Suppose we have a data set of size n=10. If we change the value of one of the
data points then it must be true that:
A) The sample mean will change
B) The sample median will change
C) The interquartile range will change
D) The range will change E) None of the Above.
9) Suppose the probability that the US economy will be in a recession next
quarter is 0.3. There is a probability of 0.2 that there will be both a recession
and a drop in consumer confidence. Given that there is a recession next
quarter, what is the probability that consumer confidence will drop?
A) 3/10
B) 2/3
C) 1/2
D) 1
E) None of the Above.
10) Suppose A and B are events with P(A)  0, P(B)  0, and P(B|A)=P(A|B).
Then it must be true that:
A) Events A, B are independent.
B) P(A)+P(B)=1.
C) P(A)=P(B) or A, B are mutually exclusive.
D) P(A)=1−P(B). E) None of the Above.
11) If events A, B are independent, then P(A)+P(B) must be equal to:
A) P(AB) B) 1 C) P(AB) D) P(AB) + P(A)P(B) E) None of the
Above.
12) For a data set of size n=10, if the range is zero it must be true that:
A) The sample mean is zero
B) The interquartile range is equal to the sample standard deviation
C) The interquartile range is greater than the sample standard deviation
D) The interquartile range is less than the sample standard deviation
E) None of the above.
13) For tomorrow in Manhattan, given that it rains, the conditional probability of
lightening striking is .4. The probability that it will rain is .3. The probability
of lightening striking is .2. Assume that it is possible to have lightening
without rain. What is the probability that there will be neither rain nor
lightening?
A) 0.12 B) 0.88 C) 0.38
D) 0.62. E) None of the Above.
14) If P( A ) > P( B ) then it must be true that:
A) P(A) > P(B). B) P(B) > P(A). C) P(A) > 1/2. D) P(B) > 1/2. E) None
of the Above.
15) A single die is thrown once. Let A={A four is thrown} and B={An even
number is thrown}. Then A, B are:
A) Independent B) mutually exclusive C) Complements of each other
D) Neither independent nor mutually exclusive E) None of the Above.