Question

From a company of 20 soldiers batches of 5 are placed on guard, each batch to watch 5 hours.For what length of time in hours can different batches be selected?

• A. ${}^2{}^9{C}_5$
• B. ${}^2{}^0{P}_5$
• C. ${}^2{}^0{C}_5\times 5$
• D. ${}^2{}^0{P}_5\times 5$

Answer 1

Answer: (C)

${}^2{}^0{C}_5\times 5$

We have to chose 5 soldiers out of 20, so number of ways of chosing soilders $={}^2{}^0{C}_5$

Now each batch is chosen to watch for 5 hours, so total time is ${}^2{}^0{C}_5\times 5$