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Finding the Fourth Proportional to 61.90, 85.38 and 39.76

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Solution

The fourth proportional to 61.90, 85.38 and 39.76 is: 54.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    61.90 : 85.38 = 39.76 : x
  2. Step 2: Convert to fraction form
    61.90/85.38 = 39.76/x
  3. Step 3: Cross multiply
    61.90x = 85.38 × 39.76
  4. Step 4: Simplify right side
    61.90x = 3,394.71
  5. Step 5: Solve for x
    x = 3,394.71/61.90
  6. Step 6: Final answer
    x = 54.84

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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.