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Finding the Fourth Proportional to 680.40, 1,020.28 and 315.36

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Solution

The fourth proportional to 680.40, 1,020.28 and 315.36 is: 472.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    680.40 : 1,020.28 = 315.36 : x
  2. Step 2: Convert to fraction form
    680.40/1,020.28 = 315.36/x
  3. Step 3: Cross multiply
    680.40x = 1,020.28 × 315.36
  4. Step 4: Simplify right side
    680.40x = 321,755.50
  5. Step 5: Solve for x
    x = 321,755.50/680.40
  6. Step 6: Final answer
    x = 472.89

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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.