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Finding the Fourth Proportional to 870.85, 1,306.60 and 408.78

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Solution

The fourth proportional to 870.85, 1,306.60 and 408.78 is: 613.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    870.85 : 1,306.60 = 408.78 : x
  2. Step 2: Convert to fraction form
    870.85/1,306.60 = 408.78/x
  3. Step 3: Cross multiply
    870.85x = 1,306.60 × 408.78
  4. Step 4: Simplify right side
    870.85x = 534,110.93
  5. Step 5: Solve for x
    x = 534,110.93/870.85
  6. Step 6: Final answer
    x = 613.32

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.