Finding the Fourth Proportional to 91.98, 138.15 and 89.10

Step by Step Solution

1. Step 1: Write the proportion equation
   91.98 : 138.15 = 89.10 : x
2. Step 2: Convert to fraction form
   91.98/138.15 = 89.10/x
3. Step 3: Cross multiply
   91.98x = 138.15 × 89.10
4. Step 4: Simplify right side
   91.98x = 12,309.17
5. Step 5: Solve for x
   x = 12,309.17/91.98
6. Step 6: Final answer
   x = 133.82