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Finding the Fourth Proportional to 141.20, 211.80 and 86.30

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Solution

The fourth proportional to 141.20, 211.80 and 86.30 is: 129.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    141.20 : 211.80 = 86.30 : x
  2. Step 2: Convert to fraction form
    141.20/211.80 = 86.30/x
  3. Step 3: Cross multiply
    141.20x = 211.80 × 86.30
  4. Step 4: Simplify right side
    141.20x = 18,278.34
  5. Step 5: Solve for x
    x = 18,278.34/141.20
  6. Step 6: Final answer
    x = 129.45

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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.