Finding the Fourth Proportional to 139.05, 191.89 and 76.88

Step by Step Solution

1. Step 1: Write the proportion equation
   139.05 : 191.89 = 76.88 : x
2. Step 2: Convert to fraction form
   139.05/191.89 = 76.88/x
3. Step 3: Cross multiply
   139.05x = 191.89 × 76.88
4. Step 4: Simplify right side
   139.05x = 14,753.33
5. Step 5: Solve for x
   x = 14,753.33/139.05
6. Step 6: Final answer
   x = 106.10