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Finding the Fourth Proportional to 811.65, 1,217.61 and 263.78

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Solution

The fourth proportional to 811.65, 1,217.61 and 263.78 is: 395.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.65 : 1,217.61 = 263.78 : x
  2. Step 2: Convert to fraction form
    811.65/1,217.61 = 263.78/x
  3. Step 3: Cross multiply
    811.65x = 1,217.61 × 263.78
  4. Step 4: Simplify right side
    811.65x = 321,175.08
  5. Step 5: Solve for x
    x = 321,175.08/811.65
  6. Step 6: Final answer
    x = 395.71

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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.