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Question 956313: A basketball player has scored 10 free throws out of 18 tries. He really wants to bring his free throw average up to at least 80%. How many consecutive free throws must he score in order to bring up his average to 80%?
I know this has something to do with rational equations, because the whole chapter we have just done for algebra 2 was about rational equations. Including: internationalizing a denominator, complex fractions, using least common denominator to simplify proportions to solve by cross multiplying. How do you solve this problem?
Answer by Theo(13342)   (Show Source):
You can put this solution on YOUR website! his average is now 10/18.
he wants to bring it up to 80%.
he will toss another x times.
since his average needs to be 80%, and since 80% is the same as .8 which is the same as 8/10, then:
(x + 10) / (x + 18) = 8/10
to solve this euatio0n, do the following:
cross multiply to get:
10 * (x + 10) = 8 * (x + 18)
simplify to get:
10x + 100 = 8x + 144
subtract 8x from both sides of the equation and subtract 100 from both sides of the equation to get:
10x - 8x = 144 - 100
simplify to get:
2x = 44
divide both sides of the equation by 2 to get:
x = 22
that's your solution.
(10 + x) / (18 + x) becomes (10 + 22) / ( 18 + 22) which becomes 32/40.
multiply 32/40 by (1/4) / (1/4) to get 8/10 is the same as .8 which is the same as 80%.
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