Finding the Fourth Proportional to 139.50, 209.16 and 48.15

Step by Step Solution

1. Step 1: Write the proportion equation
   139.50 : 209.16 = 48.15 : x
2. Step 2: Convert to fraction form
   139.50/209.16 = 48.15/x
3. Step 3: Cross multiply
   139.50x = 209.16 × 48.15
4. Step 4: Simplify right side
   139.50x = 10,071.05
5. Step 5: Solve for x
   x = 10,071.05/139.50
6. Step 6: Final answer
   x = 72.19