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Finding the Fourth Proportional to 61.78, 85.32 and 39.98

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Solution

The fourth proportional to 61.78, 85.32 and 39.98 is: 55.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    61.78 : 85.32 = 39.98 : x
  2. Step 2: Convert to fraction form
    61.78/85.32 = 39.98/x
  3. Step 3: Cross multiply
    61.78x = 85.32 × 39.98
  4. Step 4: Simplify right side
    61.78x = 3,411.09
  5. Step 5: Solve for x
    x = 3,411.09/61.78
  6. Step 6: Final answer
    x = 55.21

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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.