Finding the Fourth Proportional to 89.07, 133.31 and 78.81

Step by Step Solution

1. Step 1: Write the proportion equation
   89.07 : 133.31 = 78.81 : x
2. Step 2: Convert to fraction form
   89.07/133.31 = 78.81/x
3. Step 3: Cross multiply
   89.07x = 133.31 × 78.81
4. Step 4: Simplify right side
   89.07x = 10,505.86
5. Step 5: Solve for x
   x = 10,505.86/89.07
6. Step 6: Final answer
   x = 117.96