Finding the Fourth Proportional to 111.08, 166.34 and 78.50

Step by Step Solution

1. Step 1: Write the proportion equation
   111.08 : 166.34 = 78.50 : x
2. Step 2: Convert to fraction form
   111.08/166.34 = 78.50/x
3. Step 3: Cross multiply
   111.08x = 166.34 × 78.50
4. Step 4: Simplify right side
   111.08x = 13,057.69
5. Step 5: Solve for x
   x = 13,057.69/111.08
6. Step 6: Final answer
   x = 117.55