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Finding the Fourth Proportional to 87.36, 120.78 and 71.16

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Solution

The fourth proportional to 87.36, 120.78 and 71.16 is: 98.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.36 : 120.78 = 71.16 : x
  2. Step 2: Convert to fraction form
    87.36/120.78 = 71.16/x
  3. Step 3: Cross multiply
    87.36x = 120.78 × 71.16
  4. Step 4: Simplify right side
    87.36x = 8,594.70
  5. Step 5: Solve for x
    x = 8,594.70/87.36
  6. Step 6: Final answer
    x = 98.38

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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.