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Finding the Fourth Proportional to 489.78, 675.36 and 391.32

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Solution

The fourth proportional to 489.78, 675.36 and 391.32 is: 539.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    489.78 : 675.36 = 391.32 : x
  2. Step 2: Convert to fraction form
    489.78/675.36 = 391.32/x
  3. Step 3: Cross multiply
    489.78x = 675.36 × 391.32
  4. Step 4: Simplify right side
    489.78x = 264,281.88
  5. Step 5: Solve for x
    x = 264,281.88/489.78
  6. Step 6: Final answer
    x = 539.59

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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.