Finding the Fourth Proportional to 89.30, 133.71 and 78.50

Step by Step Solution

1. Step 1: Write the proportion equation
   89.30 : 133.71 = 78.50 : x
2. Step 2: Convert to fraction form
   89.30/133.71 = 78.50/x
3. Step 3: Cross multiply
   89.30x = 133.71 × 78.50
4. Step 4: Simplify right side
   89.30x = 10,496.24
5. Step 5: Solve for x
   x = 10,496.24/89.30
6. Step 6: Final answer
   x = 117.54