Problem 9 · 1990 AJHSME
Hard
Fractions, Decimals & Percents
count-in-rangepercent
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Answer: D — 33⅓%.
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Hint 1 of 2
Look up what a C means on the scale first: it's a score from 75 to 84. Now you're just hunting the 15 scores for the ones that land in that window.
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Hint 2 of 2
Don't compute 5/15 as an ugly decimal — simplify the fraction first. The 'percent that got a C' is just (how many C's) over 15.
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Approach: count what fits the window, then simplify the fraction
- Read the scale: a C is 75–84. Sweep the 15 scores and tally only those in that band: 77, 75, 84, 78, 80 — that's 5. (Watch the edges: 74 is a D, 85 is a B; 75 and 84 *do* count.)
- So the C fraction is 5/15. Simplify *before* converting: 5/15 = 1/3.
- One-third as a percent is 33⅓%.
- *Worth keeping:* simplify a fraction before turning it into a percent — 1/3 = 33⅓% is worth memorizing, and it dodges messy long division.
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