Finding the Fourth Proportional to 90.10, 134.06 and 89.78

Step by Step Solution

1. Step 1: Write the proportion equation
   90.10 : 134.06 = 89.78 : x
2. Step 2: Convert to fraction form
   90.10/134.06 = 89.78/x
3. Step 3: Cross multiply
   90.10x = 134.06 × 89.78
4. Step 4: Simplify right side
   90.10x = 12,035.91
5. Step 5: Solve for x
   x = 12,035.91/90.10
6. Step 6: Final answer
   x = 133.58