Finding the Fourth Proportional to 111.32, 153.72 and 83.78

Step by Step Solution

1. Step 1: Write the proportion equation
   111.32 : 153.72 = 83.78 : x
2. Step 2: Convert to fraction form
   111.32/153.72 = 83.78/x
3. Step 3: Cross multiply
   111.32x = 153.72 × 83.78
4. Step 4: Simplify right side
   111.32x = 12,877.89
5. Step 5: Solve for x
   x = 12,877.89/111.32
6. Step 6: Final answer
   x = 115.69