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Finding the Fourth Proportional to 117.20, 161.61 and 100.65

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Solution

The fourth proportional to 117.20, 161.61 and 100.65 is: 138.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    117.20 : 161.61 = 100.65 : x
  2. Step 2: Convert to fraction form
    117.20/161.61 = 100.65/x
  3. Step 3: Cross multiply
    117.20x = 161.61 × 100.65
  4. Step 4: Simplify right side
    117.20x = 16,266.05
  5. Step 5: Solve for x
    x = 16,266.05/117.20
  6. Step 6: Final answer
    x = 138.79

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.