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Finding the Fourth Proportional to 489.80, 675.99 and 312.90

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Solution

The fourth proportional to 489.80, 675.99 and 312.90 is: 431.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    489.80 : 675.99 = 312.90 : x
  2. Step 2: Convert to fraction form
    489.80/675.99 = 312.90/x
  3. Step 3: Cross multiply
    489.80x = 675.99 × 312.90
  4. Step 4: Simplify right side
    489.80x = 211,517.27
  5. Step 5: Solve for x
    x = 211,517.27/489.80
  6. Step 6: Final answer
    x = 431.85

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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.