Finding the Fourth Proportional to 111.56, 153.75 and 78.76

Step by Step Solution

1. Step 1: Write the proportion equation
   111.56 : 153.75 = 78.76 : x
2. Step 2: Convert to fraction form
   111.56/153.75 = 78.76/x
3. Step 3: Cross multiply
   111.56x = 153.75 × 78.76
4. Step 4: Simplify right side
   111.56x = 12,109.35
5. Step 5: Solve for x
   x = 12,109.35/111.56
6. Step 6: Final answer
   x = 108.55