How many pounds of salt at 50 cents/lb must be mixed with 40 lbs of salt that costs 38 cents/lb so that a merchant will get 20% profit by selling the mixture at 48 cents/lb?
Choose the most appropriate option:
A) 2
B) 5
C) 8
D) 15
E) 25

Rationale: selling price is 48 cents / lb for a 20 % profit , cost price should be 40 cents / lb ( cp * 6 / 5 = 48 ) basically , you need to mix 38 cents / lb ( salt 1 ) with 50 cents / lb ( salt 2 ) to get a mixture costing 40 cents / lb ( salt avg ) weight of salt 1 / weight of salt 2 = ( salt 2 - saltavg ) / ( saltavg - salt 1 ) = ( 50 - 40 ) / ( 40 - 38 ) = 5 / 1 we know that weight of salt 1 is 40 lbs . weight of salt 2 must be 8 lbs . answer ( c )
Answer: C