Finding the Fourth Proportional to 128.47, 192.78 and 56.32

Step by Step Solution

1. Step 1: Write the proportion equation
   128.47 : 192.78 = 56.32 : x
2. Step 2: Convert to fraction form
   128.47/192.78 = 56.32/x
3. Step 3: Cross multiply
   128.47x = 192.78 × 56.32
4. Step 4: Simplify right side
   128.47x = 10,857.37
5. Step 5: Solve for x
   x = 10,857.37/128.47
6. Step 6: Final answer
   x = 84.51