Problema Solution
The owner of a hobby store bought a case of 9-volt batteries for $56.70. He marked the price up such that his profit was $3.65 per battery. Once he had sold 14 batteries, the store owner had recovered his cost. how many 9-volt batteries are in a case?
Answer provided by our tutors
let 'x' represent the cost of a battery, then if we assume that selling 14 batteries for $3.65 per battery exactly recovered the cost of purchasing the batteries ($56.70), then:
56.70 = 14(x+3.65)
solving for 'x' we have:
x=0.4
the cost of a battery, then, was $0.40
56.70/0.40 = 141.75
...since 141.75 is not an integer, then indicates some error in the problem statement but we can claim that the case had approximately 142 batteries... a more likely correct answer would be 144 since that is a standard package type (1 gross)