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Finding the Fourth Proportional to 681.20, 1,021.20 and 407.40

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Solution

The fourth proportional to 681.20, 1,021.20 and 407.40 is: 610.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    681.20 : 1,021.20 = 407.40 : x
  2. Step 2: Convert to fraction form
    681.20/1,021.20 = 407.40/x
  3. Step 3: Cross multiply
    681.20x = 1,021.20 × 407.40
  4. Step 4: Simplify right side
    681.20x = 416,036.88
  5. Step 5: Solve for x
    x = 416,036.88/681.20
  6. Step 6: Final answer
    x = 610.74

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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.