Finding the Fourth Proportional to 139.72, 210.12 and 112.72

Step by Step Solution

1. Step 1: Write the proportion equation
   139.72 : 210.12 = 112.72 : x
2. Step 2: Convert to fraction form
   139.72/210.12 = 112.72/x
3. Step 3: Cross multiply
   139.72x = 210.12 × 112.72
4. Step 4: Simplify right side
   139.72x = 23,684.73
5. Step 5: Solve for x
   x = 23,684.73/139.72
6. Step 6: Final answer
   x = 169.52