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Finding the Fourth Proportional to 781.80, 1,078.56 and 487.44

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Solution

The fourth proportional to 781.80, 1,078.56 and 487.44 is: 672.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.80 : 1,078.56 = 487.44 : x
  2. Step 2: Convert to fraction form
    781.80/1,078.56 = 487.44/x
  3. Step 3: Cross multiply
    781.80x = 1,078.56 × 487.44
  4. Step 4: Simplify right side
    781.80x = 525,733.29
  5. Step 5: Solve for x
    x = 525,733.29/781.80
  6. Step 6: Final answer
    x = 672.47

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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.