A textbook search committee is considering
13 books for possible adoption. The committee has decided to select 3 of the 13 for further consideration. In how many ways can it do so?

Number of ways to select 3 books from 13 books for adoption is 286 .

Step-by-step explanation:

A Permutation is an ordered Combination. When the order does matter it is a Permutation. There are basically two types of permutation:

Formula is given by:

, where n is the number of things to choose from,  and we choose r of them,  no repetitions,  order matters. Here , n=13 , r=3.

⇒  

⇒  

⇒  

⇒  

⇒  

∴ Number of ways to select 3 books from 13 books for adoption is 286 .

step-by-step explanation:

given perimeter: 28cm

length: 9cm

atp,

2(l+w)=p of the reactangle

2(9+x)=28

18+2x=28

2x=28-18

x=10/2

x=5

therefore width is 5 cm