AMC 8 2006 Problem 17

AMC8 2006 年第 17 题

概率★★★☆☆

Jeff rotates spinners P , Q and R and adds the resulting numbers. What is the probability that his sum is an odd number?

Jeff 旋转转盘 P，Q 和 R，并把它们各自得到的数字相加。问所得到的和是个奇数的概率是多少？

A. $\displaystyle \frac{1}{4}$
B. $\displaystyle \frac{1}{3}$
C. $\displaystyle \frac{1}{2}$
D. $\displaystyle \frac{2}{3}$
E. $\displaystyle \frac{3}{4}$

正确答案 · Correct Answer

解析 · Solution

Solution 1

Because the sum of a number from spinner Q Q and a number from spinner R R is always odd, the sum of the numbers on the three spinners will be odd exactly when the number from spinner P P is even. Because 2 2 is the only even number on spinner P P, the probability of getting an odd sum is 1 3 3 1 . Answer: 𝐵 B .

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