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Finding the Fourth Proportional to 815.57, 1,221.26 and 540.80

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Solution

The fourth proportional to 815.57, 1,221.26 and 540.80 is: 809.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.57 : 1,221.26 = 540.80 : x
  2. Step 2: Convert to fraction form
    815.57/1,221.26 = 540.80/x
  3. Step 3: Cross multiply
    815.57x = 1,221.26 × 540.80
  4. Step 4: Simplify right side
    815.57x = 660,457.76
  5. Step 5: Solve for x
    x = 660,457.76/815.57
  6. Step 6: Final answer
    x = 809.81

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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.