Two light bulbs get mixed up with seven good ones If you tak

Two light bulbs get mixed up with seven good ones .If you take two of the bulbs , what is the probability that both are bad?

Solution

total bulbs =9

no of good ones =7

no of bad ones =2

taking 2 bulbs from 9 = 9C₂ = 9! /2!*7!

taking 2bad bulbs from 2 =2C₂ = 2!/2!*0!

probability that both are bad = 2C₂ /9C₂

   =1/36