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Finding the Fourth Proportional to 287.90, 431.39 and 280.31

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Solution

The fourth proportional to 287.90, 431.39 and 280.31 is: 420.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    287.90 : 431.39 = 280.31 : x
  2. Step 2: Convert to fraction form
    287.90/431.39 = 280.31/x
  3. Step 3: Cross multiply
    287.90x = 431.39 × 280.31
  4. Step 4: Simplify right side
    287.90x = 120,922.93
  5. Step 5: Solve for x
    x = 120,922.93/287.90
  6. Step 6: Final answer
    x = 420.02

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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.