Finding the Fourth Proportional to 105.02, 144.89 and 72.21

Step by Step Solution

1. Step 1: Write the proportion equation
   105.02 : 144.89 = 72.21 : x
2. Step 2: Convert to fraction form
   105.02/144.89 = 72.21/x
3. Step 3: Cross multiply
   105.02x = 144.89 × 72.21
4. Step 4: Simplify right side
   105.02x = 10,462.15
5. Step 5: Solve for x
   x = 10,462.15/105.02
6. Step 6: Final answer
   x = 99.63