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Finding the Fourth Proportional to 61, 84.15 and 38.90

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Solution

The fourth proportional to 61, 84.15 and 38.90 is: 53.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    61 : 84.15 = 38.90 : x
  2. Step 2: Convert to fraction form
    61/84.15 = 38.90/x
  3. Step 3: Cross multiply
    61x = 84.15 × 38.90
  4. Step 4: Simplify right side
    61x = 3,273.44
  5. Step 5: Solve for x
    x = 3,273.44/61
  6. Step 6: Final answer
    x = 53.66

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.