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Finding the Fourth Proportional to 808.40, 1,212.60 and 321.20

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Solution

The fourth proportional to 808.40, 1,212.60 and 321.20 is: 481.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    808.40 : 1,212.60 = 321.20 : x
  2. Step 2: Convert to fraction form
    808.40/1,212.60 = 321.20/x
  3. Step 3: Cross multiply
    808.40x = 1,212.60 × 321.20
  4. Step 4: Simplify right side
    808.40x = 389,487.12
  5. Step 5: Solve for x
    x = 389,487.12/808.40
  6. Step 6: Final answer
    x = 481.80

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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.