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Finding the Fourth Proportional to 815.25, 1,221.17 and 641.10

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Solution

The fourth proportional to 815.25, 1,221.17 and 641.10 is: 960.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.25 : 1,221.17 = 641.10 : x
  2. Step 2: Convert to fraction form
    815.25/1,221.17 = 641.10/x
  3. Step 3: Cross multiply
    815.25x = 1,221.17 × 641.10
  4. Step 4: Simplify right side
    815.25x = 782,888.88
  5. Step 5: Solve for x
    x = 782,888.88/815.25
  6. Step 6: Final answer
    x = 960.31

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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.