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Finding the Fourth Proportional to 77.88, 117.48 and 72.12

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Solution

The fourth proportional to 77.88, 117.48 and 72.12 is: 108.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    77.88 : 117.48 = 72.12 : x
  2. Step 2: Convert to fraction form
    77.88/117.48 = 72.12/x
  3. Step 3: Cross multiply
    77.88x = 117.48 × 72.12
  4. Step 4: Simplify right side
    77.88x = 8,472.66
  5. Step 5: Solve for x
    x = 8,472.66/77.88
  6. Step 6: Final answer
    x = 108.79

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.