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Finding the Fourth Proportional to 280.78, 421.20 and 98.15

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Solution

The fourth proportional to 280.78, 421.20 and 98.15 is: 147.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    280.78 : 421.20 = 98.15 : x
  2. Step 2: Convert to fraction form
    280.78/421.20 = 98.15/x
  3. Step 3: Cross multiply
    280.78x = 421.20 × 98.15
  4. Step 4: Simplify right side
    280.78x = 41,340.78
  5. Step 5: Solve for x
    x = 41,340.78/280.78
  6. Step 6: Final answer
    x = 147.24

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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.