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Finding the Fourth Proportional to 87.72, 121 and 61.48

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Solution

The fourth proportional to 87.72, 121 and 61.48 is: 84.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.72 : 121 = 61.48 : x
  2. Step 2: Convert to fraction form
    87.72/121 = 61.48/x
  3. Step 3: Cross multiply
    87.72x = 121 × 61.48
  4. Step 4: Simplify right side
    87.72x = 7,439.08
  5. Step 5: Solve for x
    x = 7,439.08/87.72
  6. Step 6: Final answer
    x = 84.80

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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.