jimishg wrote:

hey i am getting the answer as 12

can someone tell me ...whats wrong with this

lets the no of 10lb boxes be x

therefore no of 20 lb boxes is 30-x

10(x) + 20(30-x)/30 = 18

10(x) + 20(30-x)=540-

we get x=6 and 30-x =24

now we want the average = 14

10(x) + 20(30-x)/30=14

we get the answer x=18

there for x-18 = 12

therefore the reduction in 20 lb boxes is 24-12=12

can someone please correct me ?

10(x) + 20(30-x)/30=14 is wrong because the total number of boxes is not 30, it will be 6 + a number smaller than 24, but unknown.

I solved this problem in the same way as you, but this second equation should be: [(6*10 + 20*a)/(6+a)] = 14, where a is the number of 20lbs boxes. Solving this we obtain: a=4

Therefore 24 - 4 = 20, answer d.