Answer:
3 runners
Step-by-step explanation:
The number of runners needed is the length of the race divided by the length each runner can run:
(1/3 mi)/(1/9 mi/runner) = 9/3 runner = 3 runners
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There are a couple of ways you can divide fractions:
→ "invert and multiply." That is, multiply the numerator by the reciprocal of the denominator. Here, that is (1/3)(9/1) = 9/3 = 3
→ make the denominators the same and use the ratio of the numerators. Here that is (1/3)/(1/9) = (3/9)/(1/9) = 3/1 = 3
→ use a calculator (see attached)
