Averages

[naaga]

After 5 games, a rugby team had an average of 28 points per game. In order to increase the average by n points, how many points must be scored in a 6th game?
(A) n
(B) 6n
(C) 28n
(D) 28 + n
(E) 28 + 6n


folks need explanation...

thanks in advance

[DanaJ]

The initial average is 28, which means that, by dividing the sum of scores for the 5 games by 5, you get 28, making the total sum of scores 5*28. The new average will be equal to (total sum of scores for the 6 games)/6 = 28 + n. This means that (total sum of scores for the 6 games) = 6(28 + n) or that 5*28 + x = 6*28 + 6n (considering x = points scored in the sixth game). You can subtract 5*28 from each side and you get x = 28 + 6n.
I'd go with E. What is the OA?

[sureshbala]

If he scores 28 points in the 6th game the average will remain 28. Since we need an increase of n in the average over 6 games he needs to score 6n points more. Hence he should score 28+6n