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Finding the Fourth Proportional to 874.20, 1,207.13 and 780.78

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Solution

The fourth proportional to 874.20, 1,207.13 and 780.78 is: 1,078.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    874.20 : 1,207.13 = 780.78 : x
  2. Step 2: Convert to fraction form
    874.20/1,207.13 = 780.78/x
  3. Step 3: Cross multiply
    874.20x = 1,207.13 × 780.78
  4. Step 4: Simplify right side
    874.20x = 942,499.06
  5. Step 5: Solve for x
    x = 942,499.06/874.20
  6. Step 6: Final answer
    x = 1,078.13

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.