Question

From 1994 to 1995 the sales of a book decreased by 80% if the sales in 1996 were the same as in 1994 by what percent they inrease from 1995 to 1996

Answer 1

let 100 copies were sold in 1994
copies sold in 1995 = 100 - 80 = 20
copies sold in 1996 = 100

% increase = (100-20)/20 × 100 = 400%

Answer 2

Percentage of increase in sales from 1995 to 1996 is 400 % .

Given :

Decrease in sale from 1994 to 1995 = 80%

Sales in 1996 were the same as in 1994

To find :

Percentage by which sales increase from 1995 to 1996

Solution :

Let the sale in 1994 be x

Sales in 1995 = x - (80/100 × x)

= x - 4x/5

= (5x-4x)/5

= x/5

Sales in 1996 = x

Increase in sales from 1995 to 1996 = x-x/5

= (5x-x)/5

= 4x/5

Hence, percentage of increase in sales from 1995 to 1996 = (4x/5)÷(x/5) × 100

= (4x/5) × (5/x) × 100

= 400

Therefore, percentage of increase in sales from 1995 to 1996 is 400 % .

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