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Finding the Fourth Proportional to 122.79, 169.41 and 90

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Solution

The fourth proportional to 122.79, 169.41 and 90 is: 124.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    122.79 : 169.41 = 90 : x
  2. Step 2: Convert to fraction form
    122.79/169.41 = 90/x
  3. Step 3: Cross multiply
    122.79x = 169.41 × 90
  4. Step 4: Simplify right side
    122.79x = 15,246.90
  5. Step 5: Solve for x
    x = 15,246.90/122.79
  6. Step 6: Final answer
    x = 124.17

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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.