Alice and the Ping Pong Balls
By Page Bird
EMAT 6690
Alice bought a number of Ping-Pong
balls in a store where a 5 percent sales tax is added to every
purchase. If she did not have to pay tax, she could have bought
three more balls for the same amount of money. How many balls
did she buy?
After thinking of this problem and
trying to solve it using GSP, I came to the conclusion that an
algebraic approach would be the simplest way to approach this
problem.
Therefore, I took an algebraic approach:
p is the price of a ball and b is the number balls purchased
p* (b + 3) = 1.05*p * b
( b + 3 ) = 1.05*b
3 = 1.05*b - b
3 = .05 *b
3/ .05 = b
60 = b
So based on this, Alice bought 60 balls and she could have bought
63 balls at the same price had she not had to pay a 5% sales tax.
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