2007 AMC 8 Problems/Problem 6
Problem
The average cost of a long-distance call in the USA in was
cents per minute, and the average cost of a long-distance
call in the USA in
was
cents per minute. Find the
approximate percent decrease in the cost per minute of a long-
distance call.
Solution
The percent decrease is (the amount of decrease)/(original amount)
the amount of decrease is
so the percent decrease is which is about
,