Finding the Fourth Proportional to 105.30, 145.08 and 72.50

Step by Step Solution

1. Step 1: Write the proportion equation
   105.30 : 145.08 = 72.50 : x
2. Step 2: Convert to fraction form
   105.30/145.08 = 72.50/x
3. Step 3: Cross multiply
   105.30x = 145.08 × 72.50
4. Step 4: Simplify right side
   105.30x = 10,517.57
5. Step 5: Solve for x
   x = 10,517.57/105.30
6. Step 6: Final answer
   x = 99.88