Finding the Fourth Proportional to 127.89, 176.50 and 78.78

Step by Step Solution

1. Step 1: Write the proportion equation
   127.89 : 176.50 = 78.78 : x
2. Step 2: Convert to fraction form
   127.89/176.50 = 78.78/x
3. Step 3: Cross multiply
   127.89x = 176.50 × 78.78
4. Step 4: Simplify right side
   127.89x = 13,904.99
5. Step 5: Solve for x
   x = 13,904.99/127.89
6. Step 6: Final answer
   x = 108.73