Finding the Fourth Proportional to 111.30, 153.64 and 78.60

Step by Step Solution

1. Step 1: Write the proportion equation
   111.30 : 153.64 = 78.60 : x
2. Step 2: Convert to fraction form
   111.30/153.64 = 78.60/x
3. Step 3: Cross multiply
   111.30x = 153.64 × 78.60
4. Step 4: Simplify right side
   111.30x = 12,076.10
5. Step 5: Solve for x
   x = 12,076.10/111.30
6. Step 6: Final answer
   x = 108.50