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Finding the Fourth Proportional to 78.56, 108.80 and 77.12

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Solution

The fourth proportional to 78.56, 108.80 and 77.12 is: 106.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.56 : 108.80 = 77.12 : x
  2. Step 2: Convert to fraction form
    78.56/108.80 = 77.12/x
  3. Step 3: Cross multiply
    78.56x = 108.80 × 77.12
  4. Step 4: Simplify right side
    78.56x = 8,390.66
  5. Step 5: Solve for x
    x = 8,390.66/78.56
  6. Step 6: Final answer
    x = 106.81

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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.