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Finding the Fourth Proportional to 208.78, 313.20 and 87.10

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Solution

The fourth proportional to 208.78, 313.20 and 87.10 is: 130.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.78 : 313.20 = 87.10 : x
  2. Step 2: Convert to fraction form
    208.78/313.20 = 87.10/x
  3. Step 3: Cross multiply
    208.78x = 313.20 × 87.10
  4. Step 4: Simplify right side
    208.78x = 27,279.72
  5. Step 5: Solve for x
    x = 27,279.72/208.78
  6. Step 6: Final answer
    x = 130.66

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.