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Finding the Fourth Proportional to 61.91, 85.60 and 54.21

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Solution

The fourth proportional to 61.91, 85.60 and 54.21 is: 74.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    61.91 : 85.60 = 54.21 : x
  2. Step 2: Convert to fraction form
    61.91/85.60 = 54.21/x
  3. Step 3: Cross multiply
    61.91x = 85.60 × 54.21
  4. Step 4: Simplify right side
    61.91x = 4,640.38
  5. Step 5: Solve for x
    x = 4,640.38/61.91
  6. Step 6: Final answer
    x = 74.95

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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.