Finding the Fourth Proportional to 89.64, 134.10 and 78.12

Step by Step Solution

1. Step 1: Write the proportion equation
   89.64 : 134.10 = 78.12 : x
2. Step 2: Convert to fraction form
   89.64/134.10 = 78.12/x
3. Step 3: Cross multiply
   89.64x = 134.10 × 78.12
4. Step 4: Simplify right side
   89.64x = 10,475.89
5. Step 5: Solve for x
   x = 10,475.89/89.64
6. Step 6: Final answer
   x = 116.87