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Finding the Fourth Proportional to 123.78, 170.90 and 77.17

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Solution

The fourth proportional to 123.78, 170.90 and 77.17 is: 106.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    123.78 : 170.90 = 77.17 : x
  2. Step 2: Convert to fraction form
    123.78/170.90 = 77.17/x
  3. Step 3: Cross multiply
    123.78x = 170.90 × 77.17
  4. Step 4: Simplify right side
    123.78x = 13,188.35
  5. Step 5: Solve for x
    x = 13,188.35/123.78
  6. Step 6: Final answer
    x = 106.55

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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.