Finding the Fourth Proportional to 128.82, 193.17 and 51.78

Step by Step Solution

1. Step 1: Write the proportion equation
   128.82 : 193.17 = 51.78 : x
2. Step 2: Convert to fraction form
   128.82/193.17 = 51.78/x
3. Step 3: Cross multiply
   128.82x = 193.17 × 51.78
4. Step 4: Simplify right side
   128.82x = 10,002.34
5. Step 5: Solve for x
   x = 10,002.34/128.82
6. Step 6: Final answer
   x = 77.65