Finding the Fourth Proportional to 122.34, 168.72 and 78.68

Step by Step Solution

1. Step 1: Write the proportion equation
   122.34 : 168.72 = 78.68 : x
2. Step 2: Convert to fraction form
   122.34/168.72 = 78.68/x
3. Step 3: Cross multiply
   122.34x = 168.72 × 78.68
4. Step 4: Simplify right side
   122.34x = 13,274.89
5. Step 5: Solve for x
   x = 13,274.89/122.34
6. Step 6: Final answer
   x = 108.51