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Finding the Fourth Proportional to 870.72, 1,306.12 and 408.40

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Solution

The fourth proportional to 870.72, 1,306.12 and 408.40 is: 612.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    870.72 : 1,306.12 = 408.40 : x
  2. Step 2: Convert to fraction form
    870.72/1,306.12 = 408.40/x
  3. Step 3: Cross multiply
    870.72x = 1,306.12 × 408.40
  4. Step 4: Simplify right side
    870.72x = 533,419.41
  5. Step 5: Solve for x
    x = 533,419.41/870.72
  6. Step 6: Final answer
    x = 612.62

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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.