Question

To a box that contained 30 pencils 10 out of which were red several more non-red pencils were added. Now 25% of all pencils in this box are red. How many non-red pencils were added to the box?

Answer 1

The Amount of Non-red pencil which were added to the box = 10

Explanation:

Given as :

The number of pencils in a box = 30

The number of red pencils in a box out of 30 = 10

So , the number of Non-red pencils = 30 - 10 = 20

Again let the number of Non-red pencils which added further = x

So, now the amount of total pencil get increase to (30+x)

Among (30+x) pencils in box,25% of them are red ,

I.e The number of red pencils in a box out of (30+x) = 25% of (30+x)

And the number of Non-red pencils = 20 + x

SO, according to question

25% of (30+x) + (20+x) = (30+x)

Or, (20+x) = (30+x) - (25% of (30+x))

Or, 20+x = (30+x) [ 1 -(
`(25)/(100)`]

Or, 20+x = (30+x) (
`(3)/(4)`

Or, 80+4x = 90+3x

or 4x - 3x = 90-80

Or, x = 10

Hence the number of Non-Red pencils in the box which added further = 10 Answer