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Finding the Fourth Proportional to 680.90, 938.90 and 665.84

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Solution

The fourth proportional to 680.90, 938.90 and 665.84 is: 918.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    680.90 : 938.90 = 665.84 : x
  2. Step 2: Convert to fraction form
    680.90/938.90 = 665.84/x
  3. Step 3: Cross multiply
    680.90x = 938.90 × 665.84
  4. Step 4: Simplify right side
    680.90x = 625,149.15
  5. Step 5: Solve for x
    x = 625,149.15/680.90
  6. Step 6: Final answer
    x = 918.13

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.