Finding the Fourth Proportional to 100.88, 139.34 and 71.72

Step by Step Solution

1. Step 1: Write the proportion equation
   100.88 : 139.34 = 71.72 : x
2. Step 2: Convert to fraction form
   100.88/139.34 = 71.72/x
3. Step 3: Cross multiply
   100.88x = 139.34 × 71.72
4. Step 4: Simplify right side
   100.88x = 9,993.46
5. Step 5: Solve for x
   x = 9,993.46/100.88
6. Step 6: Final answer
   x = 99.06