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Finding the Fourth Proportional to 102.42, 140.85 and 90.79

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Solution

The fourth proportional to 102.42, 140.85 and 90.79 is: 124.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    102.42 : 140.85 = 90.79 : x
  2. Step 2: Convert to fraction form
    102.42/140.85 = 90.79/x
  3. Step 3: Cross multiply
    102.42x = 140.85 × 90.79
  4. Step 4: Simplify right side
    102.42x = 12,787.42
  5. Step 5: Solve for x
    x = 12,787.42/102.42
  6. Step 6: Final answer
    x = 124.85

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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.