Colored marbles are drawn at random from a bag without replacing any

题目

Colored marbles are drawn at random from a bag without replacing any. In the bag are four clear marbles and seven black marbles.

Quantity A

The probability of drawing two clear marbles

Quantity B

The probability of drawing three black marbles

选项

Quantity A is greater.

Quantity B is greater.

The two quantities are equal.

The relationship cannot be determined from the information given.

解析

已知：4颗透明（C）弹珠 + 7颗黑色（B）弹珠，总计11颗弹珠情况1：用基本计数原理（FCP）求解选取2颗透明弹珠：4 * 3 = 12 种可能选取3颗黑色弹珠：7 * 6 * 5 = 210 种可能情况2：用组合数求解，因为无放回抽取属于非独立事件从11颗弹珠中选取2颗透明弹珠（共4颗透明弹珠）：4C2/11C4 从11颗弹珠中选取3颗黑色弹珠（共7颗黑色弹珠）：7C3/11C7

在线客服

官方微信

公众号