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Finding the Fourth Proportional to 781.79, 1,078.65 and 615.74

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Solution

The fourth proportional to 781.79, 1,078.65 and 615.74 is: 849.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.79 : 1,078.65 = 615.74 : x
  2. Step 2: Convert to fraction form
    781.79/1,078.65 = 615.74/x
  3. Step 3: Cross multiply
    781.79x = 1,078.65 × 615.74
  4. Step 4: Simplify right side
    781.79x = 664,162.56
  5. Step 5: Solve for x
    x = 664,162.56/781.79
  6. Step 6: Final answer
    x = 849.55

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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.