Finding the Fourth Proportional to 123.89, 185.98 and 78.28

Step by Step Solution

1. Step 1: Write the proportion equation
   123.89 : 185.98 = 78.28 : x
2. Step 2: Convert to fraction form
   123.89/185.98 = 78.28/x
3. Step 3: Cross multiply
   123.89x = 185.98 × 78.28
4. Step 4: Simplify right side
   123.89x = 14,558.51
5. Step 5: Solve for x
   x = 14,558.51/123.89
6. Step 6: Final answer
   x = 117.51