Finding the Fourth Proportional to 111.78, 153.99 and 91.98

Step by Step Solution

1. Step 1: Write the proportion equation
   111.78 : 153.99 = 91.98 : x
2. Step 2: Convert to fraction form
   111.78/153.99 = 91.98/x
3. Step 3: Cross multiply
   111.78x = 153.99 × 91.98
4. Step 4: Simplify right side
   111.78x = 14,164.00
5. Step 5: Solve for x
   x = 14,164.00/111.78
6. Step 6: Final answer
   x = 126.71