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Finding the Fourth Proportional to 139.91, 209.85 and 42.40

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Solution

The fourth proportional to 139.91, 209.85 and 42.40 is: 63.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.91 : 209.85 = 42.40 : x
  2. Step 2: Convert to fraction form
    139.91/209.85 = 42.40/x
  3. Step 3: Cross multiply
    139.91x = 209.85 × 42.40
  4. Step 4: Simplify right side
    139.91x = 8,897.64
  5. Step 5: Solve for x
    x = 8,897.64/139.91
  6. Step 6: Final answer
    x = 63.60

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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.