Finding the Fourth Proportional to 139.61, 209.28 and 105.27

Step by Step Solution

1. Step 1: Write the proportion equation
   139.61 : 209.28 = 105.27 : x
2. Step 2: Convert to fraction form
   139.61/209.28 = 105.27/x
3. Step 3: Cross multiply
   139.61x = 209.28 × 105.27
4. Step 4: Simplify right side
   139.61x = 22,030.38
5. Step 5: Solve for x
   x = 22,030.38/139.61
6. Step 6: Final answer
   x = 157.80