Finding the Fourth Proportional to 111.42, 153.60 and 78.66

Step by Step Solution

1. Step 1: Write the proportion equation
   111.42 : 153.60 = 78.66 : x
2. Step 2: Convert to fraction form
   111.42/153.60 = 78.66/x
3. Step 3: Cross multiply
   111.42x = 153.60 × 78.66
4. Step 4: Simplify right side
   111.42x = 12,082.18
5. Step 5: Solve for x
   x = 12,082.18/111.42
6. Step 6: Final answer
   x = 108.44