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2019 Math Kangaroo

Problem 15

Problem 15 · 2019 Math Kangaroo Hard
Fractions, Decimals & Percents percent-multiplier

Jane plays basketball. Of her first 20 throws, 55% are successful. After five more throws her success rate rises to 56%. How many of her last five throws were successful?

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Answer: C — 3
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Hint 1 of 2
Turn each percentage into an actual number of successful throws.
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Hint 2 of 2
Subtract to find how many of the last five went in.
Show solution
Approach: convert percents to counts and subtract
  1. Of the first 20 throws, 55% = 11 were successful.
  2. After 25 throws the rate is 56%, so 0.56 × 25 = 14 successful in total.
  3. The last five contributed 14 − 11 = 3 successful throws.
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