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Finding the Fourth Proportional to 828.80, 1,243.20 and 780.80

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Solution

The fourth proportional to 828.80, 1,243.20 and 780.80 is: 1,171.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    828.80 : 1,243.20 = 780.80 : x
  2. Step 2: Convert to fraction form
    828.80/1,243.20 = 780.80/x
  3. Step 3: Cross multiply
    828.80x = 1,243.20 × 780.80
  4. Step 4: Simplify right side
    828.80x = 970,690.56
  5. Step 5: Solve for x
    x = 970,690.56/828.80
  6. Step 6: Final answer
    x = 1,171.20

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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.