Finding the Fourth Proportional to 105.15, 145.06 and 74.06

Step by Step Solution

1. Step 1: Write the proportion equation
   105.15 : 145.06 = 74.06 : x
2. Step 2: Convert to fraction form
   105.15/145.06 = 74.06/x
3. Step 3: Cross multiply
   105.15x = 145.06 × 74.06
4. Step 4: Simplify right side
   105.15x = 10,743.59
5. Step 5: Solve for x
   x = 10,743.59/105.15
6. Step 6: Final answer
   x = 102.18