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Finding the Fourth Proportional to 312.86, 469.31 and 81.74

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Solution

The fourth proportional to 312.86, 469.31 and 81.74 is: 122.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    312.86 : 469.31 = 81.74 : x
  2. Step 2: Convert to fraction form
    312.86/469.31 = 81.74/x
  3. Step 3: Cross multiply
    312.86x = 469.31 × 81.74
  4. Step 4: Simplify right side
    312.86x = 38,361.40
  5. Step 5: Solve for x
    x = 38,361.40/312.86
  6. Step 6: Final answer
    x = 122.62

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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.