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Finding the Fourth Proportional to 638.90, 881.67 and 402.80

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Solution

The fourth proportional to 638.90, 881.67 and 402.80 is: 555.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    638.90 : 881.67 = 402.80 : x
  2. Step 2: Convert to fraction form
    638.90/881.67 = 402.80/x
  3. Step 3: Cross multiply
    638.90x = 881.67 × 402.80
  4. Step 4: Simplify right side
    638.90x = 355,136.68
  5. Step 5: Solve for x
    x = 355,136.68/638.90
  6. Step 6: Final answer
    x = 555.86

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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.