Finding the Fourth Proportional to 139.18, 191.91 and 111.55

Step by Step Solution

1. Step 1: Write the proportion equation
   139.18 : 191.91 = 111.55 : x
2. Step 2: Convert to fraction form
   139.18/191.91 = 111.55/x
3. Step 3: Cross multiply
   139.18x = 191.91 × 111.55
4. Step 4: Simplify right side
   139.18x = 21,407.56
5. Step 5: Solve for x
   x = 21,407.56/139.18
6. Step 6: Final answer
   x = 153.81