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Finding the Fourth Proportional to 140.40, 210.61 and 86.20

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Solution

The fourth proportional to 140.40, 210.61 and 86.20 is: 129.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    140.40 : 210.61 = 86.20 : x
  2. Step 2: Convert to fraction form
    140.40/210.61 = 86.20/x
  3. Step 3: Cross multiply
    140.40x = 210.61 × 86.20
  4. Step 4: Simplify right side
    140.40x = 18,154.15
  5. Step 5: Solve for x
    x = 18,154.15/140.40
  6. Step 6: Final answer
    x = 129.30

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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.