Finding the Fourth Proportional to 105.06, 145.69 and 99.60

Step by Step Solution

1. Step 1: Write the proportion equation
   105.06 : 145.69 = 99.60 : x
2. Step 2: Convert to fraction form
   105.06/145.69 = 99.60/x
3. Step 3: Cross multiply
   105.06x = 145.69 × 99.60
4. Step 4: Simplify right side
   105.06x = 14,510.72
5. Step 5: Solve for x
   x = 14,510.72/105.06
6. Step 6: Final answer
   x = 138.12