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Finding the Fourth Proportional to 42.20, 62.87 and 39.87

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Solution

The fourth proportional to 42.20, 62.87 and 39.87 is: 59.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.20 : 62.87 = 39.87 : x
  2. Step 2: Convert to fraction form
    42.20/62.87 = 39.87/x
  3. Step 3: Cross multiply
    42.20x = 62.87 × 39.87
  4. Step 4: Simplify right side
    42.20x = 2,506.43
  5. Step 5: Solve for x
    x = 2,506.43/42.20
  6. Step 6: Final answer
    x = 59.40

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.