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Finding the Fourth Proportional to 781.68, 1,078.86 and 487.14

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Solution

The fourth proportional to 781.68, 1,078.86 and 487.14 is: 672.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.68 : 1,078.86 = 487.14 : x
  2. Step 2: Convert to fraction form
    781.68/1,078.86 = 487.14/x
  3. Step 3: Cross multiply
    781.68x = 1,078.86 × 487.14
  4. Step 4: Simplify right side
    781.68x = 525,555.86
  5. Step 5: Solve for x
    x = 525,555.86/781.68
  6. Step 6: Final answer
    x = 672.34

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Half scale
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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.