Section 2
1. Section 2
1.18. Explore
Section 2: Slope—Rate of Change
Explore
In Discover you developed strategies to help solve a ratio problem. You found a known ratio, 1:25, for lifeguards to swimmers. Then you used this ratio to find an unknown ratio, x:500.
One strategy to solve the problem may have been using a proportion to compare the two ratios.
Once a proportion is set up, you can rearrange or cross multiply to solve for x.
Rearrange
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Cross Multiply
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As you saw in Discover, 20 lifeguards are needed when 500 people are swimming.
As you have just seen, proportional reasoning helps relate one known ratio to find a missing term in another ratio. In Try This 2 you will use proportional reasoning to solve a problem.