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Finding the Fourth Proportional to 620.88, 855.40 and 489.84

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Solution

The fourth proportional to 620.88, 855.40 and 489.84 is: 674.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    620.88 : 855.40 = 489.84 : x
  2. Step 2: Convert to fraction form
    620.88/855.40 = 489.84/x
  3. Step 3: Cross multiply
    620.88x = 855.40 × 489.84
  4. Step 4: Simplify right side
    620.88x = 419,009.14
  5. Step 5: Solve for x
    x = 419,009.14/620.88
  6. Step 6: Final answer
    x = 674.86

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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.