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Finding the Fourth Proportional to 813.40, 1,220.78 and 326.82

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Solution

The fourth proportional to 813.40, 1,220.78 and 326.82 is: 490.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    813.40 : 1,220.78 = 326.82 : x
  2. Step 2: Convert to fraction form
    813.40/1,220.78 = 326.82/x
  3. Step 3: Cross multiply
    813.40x = 1,220.78 × 326.82
  4. Step 4: Simplify right side
    813.40x = 398,975.32
  5. Step 5: Solve for x
    x = 398,975.32/813.40
  6. Step 6: Final answer
    x = 490.50

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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.