Finding the Fourth Proportional to 123.54, 185.31 and 78.21

Step by Step Solution

1. Step 1: Write the proportion equation
   123.54 : 185.31 = 78.21 : x
2. Step 2: Convert to fraction form
   123.54/185.31 = 78.21/x
3. Step 3: Cross multiply
   123.54x = 185.31 × 78.21
4. Step 4: Simplify right side
   123.54x = 14,493.10
5. Step 5: Solve for x
   x = 14,493.10/123.54
6. Step 6: Final answer
   x = 117.32