Problem:
Juan organizes the stamps in his collection by country and by the decade in which they were issued. The prices he paid for them at a stamp shop were: Brazil and France, 6¢ each, Peru 4¢ each, and Spain 5¢ each. (Brazil and Peru are South Americal countries and France and Spain are in Europe.)
Number of Stamps by DecadeCountryBrazilFrancePeruSpain​’50s4863​’60s7449​’70s1212613​’80s815109​​Juan’s Stamp Collection
The average price of his ′70s stamps is closest to
Answer Choices:
A. 3.5¢
B. 4¢
C. 4.5¢
D. 5¢
E. 5.5¢
Solution:
The ′70s stamps cost: Brazil, 12($0.06)=$0.72; Peru, 6($0.04)=$0.24; France, 12($0.06)=$0.72; Spain, 13($0.05)=$0.65. The total is $2.33 for the 43 stamps and the average price is 43$2.33​≈$0.054≈5.54.
Answer: E​.
The problems on this page are the property of the MAA's American Mathematics Competitions