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Finding the Fourth Proportional to 305.88, 421.20 and 218.40

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Solution

The fourth proportional to 305.88, 421.20 and 218.40 is: 300.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    305.88 : 421.20 = 218.40 : x
  2. Step 2: Convert to fraction form
    305.88/421.20 = 218.40/x
  3. Step 3: Cross multiply
    305.88x = 421.20 × 218.40
  4. Step 4: Simplify right side
    305.88x = 91,990.08
  5. Step 5: Solve for x
    x = 91,990.08/305.88
  6. Step 6: Final answer
    x = 300.74

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.