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Finding the Fourth Proportional to 828.70, 1,243.20 and 280.78

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Solution

The fourth proportional to 828.70, 1,243.20 and 280.78 is: 421.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    828.70 : 1,243.20 = 280.78 : x
  2. Step 2: Convert to fraction form
    828.70/1,243.20 = 280.78/x
  3. Step 3: Cross multiply
    828.70x = 1,243.20 × 280.78
  4. Step 4: Simplify right side
    828.70x = 349,065.70
  5. Step 5: Solve for x
    x = 349,065.70/828.70
  6. Step 6: Final answer
    x = 421.22

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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.