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Finding the Fourth Proportional to 808.70, 1,212.80 and 515.78

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Solution

The fourth proportional to 808.70, 1,212.80 and 515.78 is: 773.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    808.70 : 1,212.80 = 515.78 : x
  2. Step 2: Convert to fraction form
    808.70/1,212.80 = 515.78/x
  3. Step 3: Cross multiply
    808.70x = 1,212.80 × 515.78
  4. Step 4: Simplify right side
    808.70x = 625,537.98
  5. Step 5: Solve for x
    x = 625,537.98/808.70
  6. Step 6: Final answer
    x = 773.51

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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.