Finding the Fourth Proportional to 90.18, 134.25 and 89.91

Step by Step Solution

1. Step 1: Write the proportion equation
   90.18 : 134.25 = 89.91 : x
2. Step 2: Convert to fraction form
   90.18/134.25 = 89.91/x
3. Step 3: Cross multiply
   90.18x = 134.25 × 89.91
4. Step 4: Simplify right side
   90.18x = 12,070.42
5. Step 5: Solve for x
   x = 12,070.42/90.18
6. Step 6: Final answer
   x = 133.85