SOLUTION: I have a question in my PSAT study book: "If m is 30% of n, and n is 80% of p, then m is what percent of p?" The answer choices are: 11%, 20%, 50% and 55%. I tried setting up fract

Algebra ->  Percentages: Solvers, Trainers, Word Problems and pie charts -> SOLUTION: I have a question in my PSAT study book: "If m is 30% of n, and n is 80% of p, then m is what percent of p?" The answer choices are: 11%, 20%, 50% and 55%. I tried setting up fract      Log On


   

Question 911882: I have a question in my PSAT study book: "If m is 30% of n, and n is 80% of p, then m is what percent of p?" The answer choices are: 11%, 20%, 50% and 55%. I tried setting up fractions but I get lost and I don't know what to do after that. If anyone could help me find a way to solve this problem, it would be greatly appreciated. Thank you.
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
(1) +m+=+.3n+
(2) +n+=+.8p+
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The question is:
(3) +m+=+%28+x%2F100+%29%2Ap+
Solve for +x+
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Substitute (2) into (1)
(1) +m+=+.3%2A%28+.8p+%29+
(1) +m+=+.24p+
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Substitute this result into (3)
(3) +.24p+=+%28+x%2F100+%29%2Ap+
Divide both sides by +p+
(3) +.24+=+x%2F100+
Multiply both sides by +100+
(3) +x+=+24+
m is 24% of p
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check:
(1) +m+=+.3n+
(1) +.24p+=+.3n+
(1) +n+=+.8p+
This checks out
I don't see how the answers they
gave could be correct