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Finding the Fourth Proportional to 61.66, 85.05 and 39.81

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Solution

The fourth proportional to 61.66, 85.05 and 39.81 is: 54.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    61.66 : 85.05 = 39.81 : x
  2. Step 2: Convert to fraction form
    61.66/85.05 = 39.81/x
  3. Step 3: Cross multiply
    61.66x = 85.05 × 39.81
  4. Step 4: Simplify right side
    61.66x = 3,386.16
  5. Step 5: Solve for x
    x = 3,386.16/61.66
  6. Step 6: Final answer
    x = 54.92

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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.