plz give the easiest solution i am preparing 4 bank clerk xam i have sol bt nt able 2 understand plz give detail description of how eqn is formed
The original average is the number of apples (300) divided by the number of students (let's call this "n").
Thus we begin with A1 = (300/n).
We add 10 students, which decreases the average by 1. But we still have the same number of apples.
Then the new average is A2 = (300/n+10)
We now can say A1 - A2 = 1
Substituting, we have:
(300/n) - (300/n+10) = 1
Combining the two fractions on the left, we end up with
(300n + 3000 - 300n)/n(n + 10) = 1
This reduces to
3000/n(n + 10) = 1
Simplifying, we get a quadratic equation:
n2 + 10n - 3000 = 0
(n - 50)(n + 60) = 0
Solving, we find that n = 50 or n = -60.
The negative answer is meaningless because we can't have negative students, so we select n = 50.
The original number of students was 50. Adding 10 made the number 60 and reduced the average number of apples from 6 to 5.