Question

Sir? sir? are u there? help me -_-

Answer 1

a) The easiest way is to use a calculator such as a Casio brand or Sharp brand and key in 9C7 to get 36.

However, you can also use this formula:
`nCr=(n!)/(r!(n-r)!)` where n is the total number of items and r is how many you are selecting.

Plug in values:

`(9!)/(7!(9-7)!) =(9!)/(7!*2!)=(9*8)/(2!)=36`

b) The easiest way is to use a calculator such as a Casio brand or Sharp brand and key in 9P7 to get 181440.

However, you can also use this formula:
`nPr=(n!)/((n-r)!)` where n is the total number of items and r is how many you are selecting.

Plug in values:

`(9!)/((9-7)!) =(9!)/(2!)=9*8*7*6*5*4*3=181440`