Answer:
15ways
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