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Finding the Fourth Proportional to 261.22, 391.81 and 78.62

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Solution

The fourth proportional to 261.22, 391.81 and 78.62 is: 117.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    261.22 : 391.81 = 78.62 : x
  2. Step 2: Convert to fraction form
    261.22/391.81 = 78.62/x
  3. Step 3: Cross multiply
    261.22x = 391.81 × 78.62
  4. Step 4: Simplify right side
    261.22x = 30,804.10
  5. Step 5: Solve for x
    x = 30,804.10/261.22
  6. Step 6: Final answer
    x = 117.92

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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.