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Finding the Fourth Proportional to 103.70, 142.78 and 87.29

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Solution

The fourth proportional to 103.70, 142.78 and 87.29 is: 120.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    103.70 : 142.78 = 87.29 : x
  2. Step 2: Convert to fraction form
    103.70/142.78 = 87.29/x
  3. Step 3: Cross multiply
    103.70x = 142.78 × 87.29
  4. Step 4: Simplify right side
    103.70x = 12,463.27
  5. Step 5: Solve for x
    x = 12,463.27/103.70
  6. Step 6: Final answer
    x = 120.19

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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.