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Finding the Fourth Proportional to 781.68, 1,078.94 and 487.19

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Solution

The fourth proportional to 781.68, 1,078.94 and 487.19 is: 672.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.68 : 1,078.94 = 487.19 : x
  2. Step 2: Convert to fraction form
    781.68/1,078.94 = 487.19/x
  3. Step 3: Cross multiply
    781.68x = 1,078.94 × 487.19
  4. Step 4: Simplify right side
    781.68x = 525,640.95
  5. Step 5: Solve for x
    x = 525,640.95/781.68
  6. Step 6: Final answer
    x = 672.45

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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.