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Finding the Fourth Proportional to 1,211.91, 1,672.40 and 680.80

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Solution

The fourth proportional to 1,211.91, 1,672.40 and 680.80 is: 939.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,211.91 : 1,672.40 = 680.80 : x
  2. Step 2: Convert to fraction form
    1,211.91/1,672.40 = 680.80/x
  3. Step 3: Cross multiply
    1,211.91x = 1,672.40 × 680.80
  4. Step 4: Simplify right side
    1,211.91x = 1,138,569.92
  5. Step 5: Solve for x
    x = 1,138,569.92/1,211.91
  6. Step 6: Final answer
    x = 939.48

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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.