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Finding the Fourth Proportional to 42.90, 63.90 and 42.18

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Solution

The fourth proportional to 42.90, 63.90 and 42.18 is: 62.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.90 : 63.90 = 42.18 : x
  2. Step 2: Convert to fraction form
    42.90/63.90 = 42.18/x
  3. Step 3: Cross multiply
    42.90x = 63.90 × 42.18
  4. Step 4: Simplify right side
    42.90x = 2,695.30
  5. Step 5: Solve for x
    x = 2,695.30/42.90
  6. Step 6: Final answer
    x = 62.83

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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.