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Finding the Fourth Proportional to 412.80, 619.20 and 218.40

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Solution

The fourth proportional to 412.80, 619.20 and 218.40 is: 327.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    412.80 : 619.20 = 218.40 : x
  2. Step 2: Convert to fraction form
    412.80/619.20 = 218.40/x
  3. Step 3: Cross multiply
    412.80x = 619.20 × 218.40
  4. Step 4: Simplify right side
    412.80x = 135,233.28
  5. Step 5: Solve for x
    x = 135,233.28/412.80
  6. Step 6: Final answer
    x = 327.60

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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.