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Finding the Fourth Proportional to 387.21, 534.39 and 221.43

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Solution

The fourth proportional to 387.21, 534.39 and 221.43 is: 305.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    387.21 : 534.39 = 221.43 : x
  2. Step 2: Convert to fraction form
    387.21/534.39 = 221.43/x
  3. Step 3: Cross multiply
    387.21x = 534.39 × 221.43
  4. Step 4: Simplify right side
    387.21x = 118,329.98
  5. Step 5: Solve for x
    x = 118,329.98/387.21
  6. Step 6: Final answer
    x = 305.60

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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.