1. In horse racing, a trifecta is a bet that the first three finishers in a race
ID: 3174141 • Letter: 1
Question
1. In horse racing, a trifecta is a bet that the first three finishers in a race are selected, and they are selected in the correct order. Does a trifecta involve combinations or permutations? Explain.
Choose the correct answer below.
A. Because the order of the first three finishers does not make a difference, the trifecta involves permutations.
B. Because the order of the first three finishers does make a difference, the trifecta involves permutations.
C. Because the order of the first three finishers does not make a difference, the trifecta involves combinations.
D. Because the order of the first three finishers does make a difference, the trifecta involves combinations.
2. A thief steals an ATM card and must randomly guess the correct three-digit pin code from a 9-key keypad. Repetition of digits is allowed. What is the probability of a correct guess on the first try?
The number of possible codes is__? (Type an integer or fraction. Simplify your answer.)
The probability that the correct code is given on the first try is__? (Type an integer or fraction. Simplify your answer.)
3. When testing for current in a cable with eight color-coded wires, the author used a meter to test five wires at a time. How many different tests are required for every possible pairing of five wires?
The number of tests required is__?
Explanation / Answer
2.
The number of possible code is 9*9*9 = 729
The probability that the correct code is given on the first try is
1/729 =0.00137
3. This is a "combination" problem .
Answer = 8C5 = 8! / (5! 3!) = 56 different tests are required for every possible pairing of five wires
hope that helped
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