Question

find the missing number: increased by 25% decreased by ...%

Answer 1

25% =1/4

means 4-1=3

so 3/4×100=20%

so decrease by 20%

Answer 2

Given:

A number is increased by 25%

To find:

The percentage by which it has decreased

Solution:

The percentage by which the number has to be decreased is 20%.

We can find the percentage by following the given steps-

We know that a number increased by a percentage decreases by a different percentage.

Let us assume that the number is 100.

We know that this number has been increased by 25%.

So, the new number=100+25% of 100

=100+25/100×100

=100+25

=125

Now, the new number is 125.

Let us assume that this number has to be decreased by X% to obtain 100.

So, 125-X% of 125=100

125-X/100×125=100

125-1.25X=100

125-100=1.25X

25=1.25X

25×100/125=X

2500/125=X

X=20%

Therefore, the percentage by which the number has to be decreased is 20%.