Finding the Fourth Proportional to 139.86, 209.25 and 99.23

Step by Step Solution

1. Step 1: Write the proportion equation
   139.86 : 209.25 = 99.23 : x
2. Step 2: Convert to fraction form
   139.86/209.25 = 99.23/x
3. Step 3: Cross multiply
   139.86x = 209.25 × 99.23
4. Step 4: Simplify right side
   139.86x = 20,762.83
5. Step 5: Solve for x
   x = 20,762.83/139.86
6. Step 6: Final answer
   x = 148.45