Ilanchezhiyan
If basses have to be multiple of 3, why does the question suggest that Bass =3/15(40) = 8; Does that not make Bass= 8? I am confused. Could you please explain?
Krunaal
The basses have to be a multiple of 3, because sopranos and altos need to be integers, if you consider basses to be 8 then sopranos and altos will become decimals - which is not possible. Therefore, we need at least 9 basses. There's no constraint if singers are more than 40, but we need at least 40. Hope it helps.
We are told that concert needs 40 singers, i.e. we need
at least 40 singers; and these singers should be in the ratio 5:7:3 => Total singers = \(5x + 7x + 3x = 15x\)
Now, if you take 15x = 40, x = 40/15 => you will get bases = 8, but what about sopranos and altos? 7*(40/15), and 5*(40/15) => these are decimals, and singers can't be counted as decimals. So, while it is told that the hall needs 40 singers, you cannot have
exactly 40 singers, it will be more than 40.
Therefore, when you take total no. of singers as 45, i.e. 15x =45, x = 3 => you get all proper values of all singers i.e. 15, 21, and 9. Thus, you'll have minimum a total of 45 singers, which includes 9 bases. Hope it helps.