Finding the Fourth Proportional to 139.72, 192.72 and 90.64

Step by Step Solution

1. Step 1: Write the proportion equation
   139.72 : 192.72 = 90.64 : x
2. Step 2: Convert to fraction form
   139.72/192.72 = 90.64/x
3. Step 3: Cross multiply
   139.72x = 192.72 × 90.64
4. Step 4: Simplify right side
   139.72x = 17,468.14
5. Step 5: Solve for x
   x = 17,468.14/139.72
6. Step 6: Final answer
   x = 125.02