Question

a dealer wants to mix 20kg of product A costing Rs. 2.4 per kg , with product B , worth Rs.3.3 per kg to produce a mixture worth Rs.2.7 per kg . How many kilograms of product B should he use ?

Answer 1

Cost of product A  mixed :  20 kg * Rs 2.40 =  Rs 48

let the dealer mix  N kg  of product B.
Cost of product B that was mixed :    N * Rs 3.30/kg =  Rs 3.30 N

total cost =  Rs 48 + 3.30 N
total quantity of the mixture =  20 kg + N kg

price of the mixture =  Rs 2.70

formula  for the price of the mixture =  total cost of the mixture / total quantity
               =  [ 48 + 3.30 N ] /  [20 + N ]  =  Rs 2.70
 
    So,     48 + 3.30 N =  2.70 * 20 +  N *  2.70
           0.60 N =  6

         N = 10 kg