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Finding the Fourth Proportional to 140.78, 211.20 and 76.70

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Solution

The fourth proportional to 140.78, 211.20 and 76.70 is: 115.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    140.78 : 211.20 = 76.70 : x
  2. Step 2: Convert to fraction form
    140.78/211.20 = 76.70/x
  3. Step 3: Cross multiply
    140.78x = 211.20 × 76.70
  4. Step 4: Simplify right side
    140.78x = 16,199.04
  5. Step 5: Solve for x
    x = 16,199.04/140.78
  6. Step 6: Final answer
    x = 115.07

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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.