In how many ways can a sample of 6 keyboards be selected so that exactly two have an electrical defect

15ways

Step-by-step explanation:

This is a combination question since combination has to do with selection. Hence the number of ways sample of 6 keyboards can be selected so that exactly two have an electrical defect is expressed as;

6C2 = 6!/(6-2)!2!

6C2 = 6!/4!2!

6C2 = 6×5×4!/4!×2

6C2 = 6×5/2

6C2 = 30/2

6C2 = 15

Hence this can be done in 15ways

2x + 40

Step-by-step explanation:

2x+4+x+10-x

= 2x + 40