E. None of these.
____19. If one card is randomly picked from a standard deck of 52 cards, the probability that the card be a red suit or a face (Jack,
Queen, King) card is:
A. 50%
B. 61.5%
C. 76.9%
D. 88.5%
E. 91.2%
____20. Students at University X must be in one of the class ranks—freshman, sophomore, junior, or senior.
At University X, 35% of
the students are freshmen and 30% are sophomores.
If a student is selected at random, the probability that he or she is either a junior
or senior is:
A.
30%
B. 35%
C. 65%
D. 70%
E. Can not be determined
21. You have a two-part multiple choice test tomorrow, with 10 questions on one part and 10 questions on the other; all questions have
4 choices. You don’t have time to study the entire material well. From your past…
Strategy 1: you know that if you study all of the material in the time you have, you can narrow all 20 questions down to two answer
choices and get them correct with probability of 0.5.
Strategy 2: you know that if you study only the first set of material well, you will get the first 10 questions right of the first part with
probability of 0.8 but will have to guess randomly on the second part of the remaining 10 questions.
a. What is the expected grade using Strategy 1? What’s the standard deviation?
b. What is the expected grade using Strategy 2? What’s the standard deviation?

c. Compare the two strategies statistically as to which strategy is better or not.

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- Summer '16
- Calculus