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Finding the Fourth Proportional to 666.89, 920.19 and 387.15

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Solution

The fourth proportional to 666.89, 920.19 and 387.15 is: 534.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    666.89 : 920.19 = 387.15 : x
  2. Step 2: Convert to fraction form
    666.89/920.19 = 387.15/x
  3. Step 3: Cross multiply
    666.89x = 920.19 × 387.15
  4. Step 4: Simplify right side
    666.89x = 356,251.56
  5. Step 5: Solve for x
    x = 356,251.56/666.89
  6. Step 6: Final answer
    x = 534.20

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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.