Finding the Fourth Proportional to 123.10, 168.78 and 120.91

Step by Step Solution

1. Step 1: Write the proportion equation
   123.10 : 168.78 = 120.91 : x
2. Step 2: Convert to fraction form
   123.10/168.78 = 120.91/x
3. Step 3: Cross multiply
   123.10x = 168.78 × 120.91
4. Step 4: Simplify right side
   123.10x = 20,406.77
5. Step 5: Solve for x
   x = 20,406.77/123.10
6. Step 6: Final answer
   x = 165.77