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Finding the Fourth Proportional to 861.76, 1,189.34 and 721.64

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Solution

The fourth proportional to 861.76, 1,189.34 and 721.64 is: 995.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.76 : 1,189.34 = 721.64 : x
  2. Step 2: Convert to fraction form
    861.76/1,189.34 = 721.64/x
  3. Step 3: Cross multiply
    861.76x = 1,189.34 × 721.64
  4. Step 4: Simplify right side
    861.76x = 858,275.32
  5. Step 5: Solve for x
    x = 858,275.32/861.76
  6. Step 6: Final answer
    x = 995.96

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Double scale
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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.