Finding the Fourth Proportional to 99.39, 149.18 and 72.21

Step by Step Solution

1. Step 1: Write the proportion equation
   99.39 : 149.18 = 72.21 : x
2. Step 2: Convert to fraction form
   99.39/149.18 = 72.21/x
3. Step 3: Cross multiply
   99.39x = 149.18 × 72.21
4. Step 4: Simplify right side
   99.39x = 10,771.93
5. Step 5: Solve for x
   x = 10,771.93/99.39
6. Step 6: Final answer
   x = 108.38