Finding the Fourth Proportional to 128.37, 192.59 and 55.21

Step by Step Solution

1. Step 1: Write the proportion equation
   128.37 : 192.59 = 55.21 : x
2. Step 2: Convert to fraction form
   128.37/192.59 = 55.21/x
3. Step 3: Cross multiply
   128.37x = 192.59 × 55.21
4. Step 4: Simplify right side
   128.37x = 10,633.02
5. Step 5: Solve for x
   x = 10,633.02/128.37
6. Step 6: Final answer
   x = 82.83