Finding the Fourth Proportional to 139.91, 209.71 and 71.34

Step by Step Solution

1. Step 1: Write the proportion equation
   139.91 : 209.71 = 71.34 : x
2. Step 2: Convert to fraction form
   139.91/209.71 = 71.34/x
3. Step 3: Cross multiply
   139.91x = 209.71 × 71.34
4. Step 4: Simplify right side
   139.91x = 14,959.48
5. Step 5: Solve for x
   x = 14,959.48/139.91
6. Step 6: Final answer
   x = 106.92