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Finding the Fourth Proportional to 986.20, 1,479.28 and 255.78

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Solution

The fourth proportional to 986.20, 1,479.28 and 255.78 is: 383.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    986.20 : 1,479.28 = 255.78 : x
  2. Step 2: Convert to fraction form
    986.20/1,479.28 = 255.78/x
  3. Step 3: Cross multiply
    986.20x = 1,479.28 × 255.78
  4. Step 4: Simplify right side
    986.20x = 378,370.24
  5. Step 5: Solve for x
    x = 378,370.24/986.20
  6. Step 6: Final answer
    x = 383.66

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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.