Finding the Fourth Proportional to 89.61, 122.78 and 86.37

Step by Step Solution

1. Step 1: Write the proportion equation
   89.61 : 122.78 = 86.37 : x
2. Step 2: Convert to fraction form
   89.61/122.78 = 86.37/x
3. Step 3: Cross multiply
   89.61x = 122.78 × 86.37
4. Step 4: Simplify right side
   89.61x = 10,604.08
5. Step 5: Solve for x
   x = 10,604.08/89.61
6. Step 6: Final answer
   x = 118.34