Question

A consumer testing service is commissioned to rank the top 3 brands of laundry detergent. A total of 10 brands are to be included in the study. In how many ways can the consumer testing service arrive at the final ranking

Answer 1

120ways

Explanation:

This question bothers combination. Combination has to do with selection.

Given

Total number of brands = 10

If we the service is to rank the top 3, this can be done in 10C3 number of ways.

10C3 = 10!/(10-3)!3!

10C 3 = 10!/7!3!

10C3 = 10*9*8*7!/7!3!

10C3 = 10*9*8/6

10C3 = 720/6

10C3 = 120

Hence it will take 120ways for the consumer testing service to arrive at the final ranking