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Finding the Fourth Proportional to 855.20, 1,282.80 and 721.55

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Solution

The fourth proportional to 855.20, 1,282.80 and 721.55 is: 1,082.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    855.20 : 1,282.80 = 721.55 : x
  2. Step 2: Convert to fraction form
    855.20/1,282.80 = 721.55/x
  3. Step 3: Cross multiply
    855.20x = 1,282.80 × 721.55
  4. Step 4: Simplify right side
    855.20x = 925,604.34
  5. Step 5: Solve for x
    x = 925,604.34/855.20
  6. Step 6: Final answer
    x = 1,082.33

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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.