Finding the Fourth Proportional to 105.39, 145.71 and 86.94

Step by Step Solution

1. Step 1: Write the proportion equation
   105.39 : 145.71 = 86.94 : x
2. Step 2: Convert to fraction form
   105.39/145.71 = 86.94/x
3. Step 3: Cross multiply
   105.39x = 145.71 × 86.94
4. Step 4: Simplify right side
   105.39x = 12,668.03
5. Step 5: Solve for x
   x = 12,668.03/105.39
6. Step 6: Final answer
   x = 120.20