Finding the Fourth Proportional to 139.72, 209.57 and 48.42

Step by Step Solution

1. Step 1: Write the proportion equation
   139.72 : 209.57 = 48.42 : x
2. Step 2: Convert to fraction form
   139.72/209.57 = 48.42/x
3. Step 3: Cross multiply
   139.72x = 209.57 × 48.42
4. Step 4: Simplify right side
   139.72x = 10,147.38
5. Step 5: Solve for x
   x = 10,147.38/139.72
6. Step 6: Final answer
   x = 72.63