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Finding the Fourth Proportional to 280.80, 421.08 and 143.78

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Solution

The fourth proportional to 280.80, 421.08 and 143.78 is: 215.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    280.80 : 421.08 = 143.78 : x
  2. Step 2: Convert to fraction form
    280.80/421.08 = 143.78/x
  3. Step 3: Cross multiply
    280.80x = 421.08 × 143.78
  4. Step 4: Simplify right side
    280.80x = 60,540.78
  5. Step 5: Solve for x
    x = 60,540.78/280.80
  6. Step 6: Final answer
    x = 215.60

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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.