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Finding the Fourth Proportional to 61.86, 85.31 and 39.99

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Solution

The fourth proportional to 61.86, 85.31 and 39.99 is: 55.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    61.86 : 85.31 = 39.99 : x
  2. Step 2: Convert to fraction form
    61.86/85.31 = 39.99/x
  3. Step 3: Cross multiply
    61.86x = 85.31 × 39.99
  4. Step 4: Simplify right side
    61.86x = 3,411.50
  5. Step 5: Solve for x
    x = 3,411.50/61.86
  6. Step 6: Final answer
    x = 55.15

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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.