Finding the Fourth Proportional to 101.28, 139.82 and 72.12

Step by Step Solution

1. Step 1: Write the proportion equation
   101.28 : 139.82 = 72.12 : x
2. Step 2: Convert to fraction form
   101.28/139.82 = 72.12/x
3. Step 3: Cross multiply
   101.28x = 139.82 × 72.12
4. Step 4: Simplify right side
   101.28x = 10,083.82
5. Step 5: Solve for x
   x = 10,083.82/101.28
6. Step 6: Final answer
   x = 99.56