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Finding the Fourth Proportional to 78.43, 108.21 and 55.12

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Solution

The fourth proportional to 78.43, 108.21 and 55.12 is: 76.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.43 : 108.21 = 55.12 : x
  2. Step 2: Convert to fraction form
    78.43/108.21 = 55.12/x
  3. Step 3: Cross multiply
    78.43x = 108.21 × 55.12
  4. Step 4: Simplify right side
    78.43x = 5,964.54
  5. Step 5: Solve for x
    x = 5,964.54/78.43
  6. Step 6: Final answer
    x = 76.05

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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.