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Finding the Fourth Proportional to 812.20, 1,215.60 and 747.40

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Solution

The fourth proportional to 812.20, 1,215.60 and 747.40 is: 1,118.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    812.20 : 1,215.60 = 747.40 : x
  2. Step 2: Convert to fraction form
    812.20/1,215.60 = 747.40/x
  3. Step 3: Cross multiply
    812.20x = 1,215.60 × 747.40
  4. Step 4: Simplify right side
    812.20x = 908,539.44
  5. Step 5: Solve for x
    x = 908,539.44/812.20
  6. Step 6: Final answer
    x = 1,118.62

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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.