A leather pouch contains 10 light bulbs, two of which are defective

题目

A leather pouch contains 10 light bulbs, two of which are defective.

Quantity A

The probability of drawing two defective light bulbs (without replacement)

Quantity B

The probability of drawing two defective light bulbs (without replacement) and then a non-defective bulb

选项

The quantity in Column A is greater.

The quantity in Column B is greater.

The two quantities are equal.

The relationship cannot be determined from the information given.

解析

答案：C 10个灯泡：8个合格品 + 2个次品 A：不放回抽取2个次品灯泡的概率：第一次抽到次品的概率为2/10，第二次抽到次品的概率为1/9，因此A的值为：2/10 × 1/9 = 2/90 B：不放回抽取2个次品灯泡，再抽取1个合格品灯泡的概率：第一次抽到次品的概率为2/10，第二次抽到次品的概率为1/9，第三次抽取时，2个次品已被抽走，剩余8个均为合格品，抽到合格品的概率为8/8，因此B的值为：2/10 × 1/9 × 8/8 = 2/90 A与B的值相等，答案为C。

在线客服

官方微信

公众号