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Finding the Fourth Proportional to 813.78, 1,221.08 and 326.84

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Solution

The fourth proportional to 813.78, 1,221.08 and 326.84 is: 490.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    813.78 : 1,221.08 = 326.84 : x
  2. Step 2: Convert to fraction form
    813.78/1,221.08 = 326.84/x
  3. Step 3: Cross multiply
    813.78x = 1,221.08 × 326.84
  4. Step 4: Simplify right side
    813.78x = 399,090.05
  5. Step 5: Solve for x
    x = 399,090.05/813.78
  6. Step 6: Final answer
    x = 490.42

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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.