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Finding the Fourth Proportional to 813.15, 1,220.40 and 326.57

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Solution

The fourth proportional to 813.15, 1,220.40 and 326.57 is: 490.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    813.15 : 1,220.40 = 326.57 : x
  2. Step 2: Convert to fraction form
    813.15/1,220.40 = 326.57/x
  3. Step 3: Cross multiply
    813.15x = 1,220.40 × 326.57
  4. Step 4: Simplify right side
    813.15x = 398,539.93
  5. Step 5: Solve for x
    x = 398,539.93/813.15
  6. Step 6: Final answer
    x = 490.12

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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.