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Finding the Fourth Proportional to 489.90, 680.61 and 485.40

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Solution

The fourth proportional to 489.90, 680.61 and 485.40 is: 674.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    489.90 : 680.61 = 485.40 : x
  2. Step 2: Convert to fraction form
    489.90/680.61 = 485.40/x
  3. Step 3: Cross multiply
    489.90x = 680.61 × 485.40
  4. Step 4: Simplify right side
    489.90x = 330,368.09
  5. Step 5: Solve for x
    x = 330,368.09/489.90
  6. Step 6: Final answer
    x = 674.36

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.