at a certain food stand , the price of each apple is 40 ¢ and the price of each orange is 60 ¢ . mary selects a total of 10 apples and oranges from the food stand , and the average ( arithmetic mean ) price of the 10 pieces of fruit is 52 ¢ . how many oranges must mary put back so that the average price of the pieces of fruit that she keeps is 44 ¢ ?
if the average price is 52 , then mary has 6 oranges and 4 apples ( a ratio of 3 : 2 ) . for the average price to be 44 , the ratio should be 1 : 4 . mary must put back 5 oranges . the answer is e .
divide(subtract(add(multiply(divide(subtract(multiply(60, 10), multiply(52, 10)), subtract(60, 40)), 40), multiply(subtract(10, divide(subtract(multiply(60, 10), multiply(52, 10)), subtract(60, 40))), 60)), multiply(44, 10)), subtract(60, 44))