Finding the Fourth Proportional to 105.72, 145.74 and 83.55

Step by Step Solution

1. Step 1: Write the proportion equation
   105.72 : 145.74 = 83.55 : x
2. Step 2: Convert to fraction form
   105.72/145.74 = 83.55/x
3. Step 3: Cross multiply
   105.72x = 145.74 × 83.55
4. Step 4: Simplify right side
   105.72x = 12,176.81
5. Step 5: Solve for x
   x = 12,176.81/105.72
6. Step 6: Final answer
   x = 115.18