Finding the Fourth Proportional to 128.55, 192.91 and 56.42

Step by Step Solution

1. Step 1: Write the proportion equation
   128.55 : 192.91 = 56.42 : x
2. Step 2: Convert to fraction form
   128.55/192.91 = 56.42/x
3. Step 3: Cross multiply
   128.55x = 192.91 × 56.42
4. Step 4: Simplify right side
   128.55x = 10,883.98
5. Step 5: Solve for x
   x = 10,883.98/128.55
6. Step 6: Final answer
   x = 84.67