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Finding the Fourth Proportional to 681.76, 1,021.56 and 388.72

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Solution

The fourth proportional to 681.76, 1,021.56 and 388.72 is: 582.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    681.76 : 1,021.56 = 388.72 : x
  2. Step 2: Convert to fraction form
    681.76/1,021.56 = 388.72/x
  3. Step 3: Cross multiply
    681.76x = 1,021.56 × 388.72
  4. Step 4: Simplify right side
    681.76x = 397,100.80
  5. Step 5: Solve for x
    x = 397,100.80/681.76
  6. Step 6: Final answer
    x = 582.46

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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.