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Finding the Fourth Proportional to 489.58, 675.84 and 312.78

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Solution

The fourth proportional to 489.58, 675.84 and 312.78 is: 431.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    489.58 : 675.84 = 312.78 : x
  2. Step 2: Convert to fraction form
    489.58/675.84 = 312.78/x
  3. Step 3: Cross multiply
    489.58x = 675.84 × 312.78
  4. Step 4: Simplify right side
    489.58x = 211,387.38
  5. Step 5: Solve for x
    x = 211,387.38/489.58
  6. Step 6: Final answer
    x = 431.78

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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.