Finding the Fourth Proportional to 111.42, 153.78 and 78.62

Step by Step Solution

1. Step 1: Write the proportion equation
   111.42 : 153.78 = 78.62 : x
2. Step 2: Convert to fraction form
   111.42/153.78 = 78.62/x
3. Step 3: Cross multiply
   111.42x = 153.78 × 78.62
4. Step 4: Simplify right side
   111.42x = 12,090.18
5. Step 5: Solve for x
   x = 12,090.18/111.42
6. Step 6: Final answer
   x = 108.51