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Finding the Fourth Proportional to 87.48, 120.80 and 83.40

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Solution

The fourth proportional to 87.48, 120.80 and 83.40 is: 115.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.48 : 120.80 = 83.40 : x
  2. Step 2: Convert to fraction form
    87.48/120.80 = 83.40/x
  3. Step 3: Cross multiply
    87.48x = 120.80 × 83.40
  4. Step 4: Simplify right side
    87.48x = 10,074.72
  5. Step 5: Solve for x
    x = 10,074.72/87.48
  6. Step 6: Final answer
    x = 115.17

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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.