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Finding the Fourth Proportional to 681.28, 1,021.40 and 315.80

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Solution

The fourth proportional to 681.28, 1,021.40 and 315.80 is: 473.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    681.28 : 1,021.40 = 315.80 : x
  2. Step 2: Convert to fraction form
    681.28/1,021.40 = 315.80/x
  3. Step 3: Cross multiply
    681.28x = 1,021.40 × 315.80
  4. Step 4: Simplify right side
    681.28x = 322,558.12
  5. Step 5: Solve for x
    x = 322,558.12/681.28
  6. Step 6: Final answer
    x = 473.46

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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.