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Finding the Fourth Proportional to 87.49, 120.74 and 56.42

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Solution

The fourth proportional to 87.49, 120.74 and 56.42 is: 77.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.49 : 120.74 = 56.42 : x
  2. Step 2: Convert to fraction form
    87.49/120.74 = 56.42/x
  3. Step 3: Cross multiply
    87.49x = 120.74 × 56.42
  4. Step 4: Simplify right side
    87.49x = 6,812.15
  5. Step 5: Solve for x
    x = 6,812.15/87.49
  6. Step 6: Final answer
    x = 77.86

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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.