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Finding the Fourth Proportional to 681.35, 1,020.67 and 420.80

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Solution

The fourth proportional to 681.35, 1,020.67 and 420.80 is: 630.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    681.35 : 1,020.67 = 420.80 : x
  2. Step 2: Convert to fraction form
    681.35/1,020.67 = 420.80/x
  3. Step 3: Cross multiply
    681.35x = 1,020.67 × 420.80
  4. Step 4: Simplify right side
    681.35x = 429,491.78
  5. Step 5: Solve for x
    x = 429,491.78/681.35
  6. Step 6: Final answer
    x = 630.36

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.