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Finding the Fourth Proportional to 680.90, 1,020.74 and 315.39

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Solution

The fourth proportional to 680.90, 1,020.74 and 315.39 is: 472.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    680.90 : 1,020.74 = 315.39 : x
  2. Step 2: Convert to fraction form
    680.90/1,020.74 = 315.39/x
  3. Step 3: Cross multiply
    680.90x = 1,020.74 × 315.39
  4. Step 4: Simplify right side
    680.90x = 321,924.51
  5. Step 5: Solve for x
    x = 321,924.51/680.90
  6. Step 6: Final answer
    x = 472.80

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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.