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Finding the Fourth Proportional to 140.78, 211.30 and 86.78

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Solution

The fourth proportional to 140.78, 211.30 and 86.78 is: 130.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    140.78 : 211.30 = 86.78 : x
  2. Step 2: Convert to fraction form
    140.78/211.30 = 86.78/x
  3. Step 3: Cross multiply
    140.78x = 211.30 × 86.78
  4. Step 4: Simplify right side
    140.78x = 18,336.61
  5. Step 5: Solve for x
    x = 18,336.61/140.78
  6. Step 6: Final answer
    x = 130.25

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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.