Average problem

[phoenix9801]

1-
Each of the 30 programs on sale for download costs either $10 or $20. The average price of these programs is $18. How many $20 programs must be removed from the sale to reduce the average sale price of the remaining programs to $14?

A) 24
B) 20
C) 10
D) 6
E) 4

[Jim@StratusPrep]

FiRat figure current nmbera. Since 18 is 80% of the way from 10 to 20. 80% of the magazines, or 24 are priced at 20. So, 6 are priced at 12 and need to be 40% of the total. 6 is 40% of 15 -- this leaves 9 priced at 20. We must remove 15 to get to 9

[Jim@StratusPrep]

Sorry. Last bit is 60% are priced at 10. 6 is 60% of ten, so 20 programs must be removed to leave 10.