Finding the Fourth Proportional to 89.38, 133.98 and 78.58

Step by Step Solution

1. Step 1: Write the proportion equation
   89.38 : 133.98 = 78.58 : x
2. Step 2: Convert to fraction form
   89.38/133.98 = 78.58/x
3. Step 3: Cross multiply
   89.38x = 133.98 × 78.58
4. Step 4: Simplify right side
   89.38x = 10,528.15
5. Step 5: Solve for x
   x = 10,528.15/89.38
6. Step 6: Final answer
   x = 117.79