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Finding the Fourth Proportional to 681.70, 1,020.12 and 391.72

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Solution

The fourth proportional to 681.70, 1,020.12 and 391.72 is: 586.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    681.70 : 1,020.12 = 391.72 : x
  2. Step 2: Convert to fraction form
    681.70/1,020.12 = 391.72/x
  3. Step 3: Cross multiply
    681.70x = 1,020.12 × 391.72
  4. Step 4: Simplify right side
    681.70x = 399,601.41
  5. Step 5: Solve for x
    x = 399,601.41/681.70
  6. Step 6: Final answer
    x = 586.18

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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.