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Finding the Fourth Proportional to 681.12, 1,021.82 and 218.78

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Solution

The fourth proportional to 681.12, 1,021.82 and 218.78 is: 328.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    681.12 : 1,021.82 = 218.78 : x
  2. Step 2: Convert to fraction form
    681.12/1,021.82 = 218.78/x
  3. Step 3: Cross multiply
    681.12x = 1,021.82 × 218.78
  4. Step 4: Simplify right side
    681.12x = 223,551.41
  5. Step 5: Solve for x
    x = 223,551.41/681.12
  6. Step 6: Final answer
    x = 328.21

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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.