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Finding the Fourth Proportional to 489.89, 675.90 and 312.90

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Solution

The fourth proportional to 489.89, 675.90 and 312.90 is: 431.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    489.89 : 675.90 = 312.90 : x
  2. Step 2: Convert to fraction form
    489.89/675.90 = 312.90/x
  3. Step 3: Cross multiply
    489.89x = 675.90 × 312.90
  4. Step 4: Simplify right side
    489.89x = 211,489.11
  5. Step 5: Solve for x
    x = 211,489.11/489.89
  6. Step 6: Final answer
    x = 431.71

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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.