Finding the Fourth Proportional to 91.21, 136.41 and 89.05

Step by Step Solution

1. Step 1: Write the proportion equation
   91.21 : 136.41 = 89.05 : x
2. Step 2: Convert to fraction form
   91.21/136.41 = 89.05/x
3. Step 3: Cross multiply
   91.21x = 136.41 × 89.05
4. Step 4: Simplify right side
   91.21x = 12,147.31
5. Step 5: Solve for x
   x = 12,147.31/91.21
6. Step 6: Final answer
   x = 133.18