Finding the Fourth Proportional to 105.49, 145.61 and 72.79

Step by Step Solution

1. Step 1: Write the proportion equation
   105.49 : 145.61 = 72.79 : x
2. Step 2: Convert to fraction form
   105.49/145.61 = 72.79/x
3. Step 3: Cross multiply
   105.49x = 145.61 × 72.79
4. Step 4: Simplify right side
   105.49x = 10,598.95
5. Step 5: Solve for x
   x = 10,598.95/105.49
6. Step 6: Final answer
   x = 100.47