Finding the Fourth Proportional to 111.99, 154.47 and 78.75

Step by Step Solution

1. Step 1: Write the proportion equation
   111.99 : 154.47 = 78.75 : x
2. Step 2: Convert to fraction form
   111.99/154.47 = 78.75/x
3. Step 3: Cross multiply
   111.99x = 154.47 × 78.75
4. Step 4: Simplify right side
   111.99x = 12,164.51
5. Step 5: Solve for x
   x = 12,164.51/111.99
6. Step 6: Final answer
   x = 108.62