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Finding the Fourth Proportional to 828, 1,242 and 315.12

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Solution

The fourth proportional to 828, 1,242 and 315.12 is: 472.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    828 : 1,242 = 315.12 : x
  2. Step 2: Convert to fraction form
    828/1,242 = 315.12/x
  3. Step 3: Cross multiply
    828x = 1,242 × 315.12
  4. Step 4: Simplify right side
    828x = 391,379.04
  5. Step 5: Solve for x
    x = 391,379.04/828
  6. Step 6: Final answer
    x = 472.68

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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.