Finding the Fourth Proportional to 111.50, 153.78 and 91.79

Step by Step Solution

1. Step 1: Write the proportion equation
   111.50 : 153.78 = 91.79 : x
2. Step 2: Convert to fraction form
   111.50/153.78 = 91.79/x
3. Step 3: Cross multiply
   111.50x = 153.78 × 91.79
4. Step 4: Simplify right side
   111.50x = 14,115.47
5. Step 5: Solve for x
   x = 14,115.47/111.50
6. Step 6: Final answer
   x = 126.60