After increase in the price of coffee by 15%, a person is able to buy 3 kg less for Rs. 1,840. Find the original and increased price of the coffee per kg?
Let the original price (O.P.) be Rs. x per kg.
New price (N.P.) = 115% of x = Rs. 23x/20 per kg.
Quantity of coffee the person could buy at original price = 1840/ x kg.
Quantity of coffee he can buy at new price = 1840 × 20/ (23x) = 1600/x kg
Given that difference between the quantity at original price and at new price is 3 kg.
1840/ x - 1600/ x = 3 ⇒ 240/ x = 3 ⇒ x = 80
O.P. = Rs.80 and N.P. = Rs. 23x/ 20 = 23 × 80/20 = Rs.92
Alternate method:
Increase price = RS × change in price change in quanity = (1840×15%)/ 3 = 92
Now original price : increased price = 100 : 115 = x : 92
So x = 100×92/115 = Rs 80
So original price = Rs 80 & increased price = Rs. 92
