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Finding the Fourth Proportional to 123.91, 171.02 and 77.31

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Solution

The fourth proportional to 123.91, 171.02 and 77.31 is: 106.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    123.91 : 171.02 = 77.31 : x
  2. Step 2: Convert to fraction form
    123.91/171.02 = 77.31/x
  3. Step 3: Cross multiply
    123.91x = 171.02 × 77.31
  4. Step 4: Simplify right side
    123.91x = 13,221.56
  5. Step 5: Solve for x
    x = 13,221.56/123.91
  6. Step 6: Final answer
    x = 106.70

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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.