Finding the Fourth Proportional to 105.60, 145.56 and 86.16

Step by Step Solution

1. Step 1: Write the proportion equation
   105.60 : 145.56 = 86.16 : x
2. Step 2: Convert to fraction form
   105.60/145.56 = 86.16/x
3. Step 3: Cross multiply
   105.60x = 145.56 × 86.16
4. Step 4: Simplify right side
   105.60x = 12,541.45
5. Step 5: Solve for x
   x = 12,541.45/105.60
6. Step 6: Final answer
   x = 118.76