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Finding the Fourth Proportional to 815.40, 1,221.89 and 568.15

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Solution

The fourth proportional to 815.40, 1,221.89 and 568.15 is: 851.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.40 : 1,221.89 = 568.15 : x
  2. Step 2: Convert to fraction form
    815.40/1,221.89 = 568.15/x
  3. Step 3: Cross multiply
    815.40x = 1,221.89 × 568.15
  4. Step 4: Simplify right side
    815.40x = 694,210.91
  5. Step 5: Solve for x
    x = 694,210.91/815.40
  6. Step 6: Final answer
    x = 851.37

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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.