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Finding the Fourth Proportional to 680.67, 1,020.75 and 315.21

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Solution

The fourth proportional to 680.67, 1,020.75 and 315.21 is: 472.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    680.67 : 1,020.75 = 315.21 : x
  2. Step 2: Convert to fraction form
    680.67/1,020.75 = 315.21/x
  3. Step 3: Cross multiply
    680.67x = 1,020.75 × 315.21
  4. Step 4: Simplify right side
    680.67x = 321,750.61
  5. Step 5: Solve for x
    x = 321,750.61/680.67
  6. Step 6: Final answer
    x = 472.70

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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.