AMC8 2009

AMC8 2009 · Q12

AMC8 2009 · Q12. It mainly tests Probability (basic), Primes & prime factorization.

The two spinners shown are spun once and each lands on one of the numbered sectors. What is the probability that the sum of the numbers in the two sectors is prime?

示出的两个转盘各转动一次，每个都落在编号扇形之一上。两个扇形数字之和为质数的概率是多少？

(A) \frac{1}{2} \frac{1}{2}

(B) \frac{2}{3} \frac{2}{3}

(D) \frac{7}{9} \frac{7}{9}

(E) \frac{5}{6} \frac{5}{6}

Answer

Correct choice: (D)

正确答案：（D）

Solution

The table shows that seven of the nine equally likely events have prime numbers for their outcomes. So the probability of a prime outcome is $\frac{7}{9}$.

该表显示，九个等可能事件中有七个事件的结果是质数。因此，得到质数结果的概率是 $\frac{7}{9}$。

Topics