Finding the Fourth Proportional to 90.78, 136.18 and 74.72

Step by Step Solution

1. Step 1: Write the proportion equation
   90.78 : 136.18 = 74.72 : x
2. Step 2: Convert to fraction form
   90.78/136.18 = 74.72/x
3. Step 3: Cross multiply
   90.78x = 136.18 × 74.72
4. Step 4: Simplify right side
   90.78x = 10,175.01
5. Step 5: Solve for x
   x = 10,175.01/90.78
6. Step 6: Final answer
   x = 112.08