Finding the Fourth Proportional to 105.64, 145.72 and 83.72

Step by Step Solution

1. Step 1: Write the proportion equation
   105.64 : 145.72 = 83.72 : x
2. Step 2: Convert to fraction form
   105.64/145.72 = 83.72/x
3. Step 3: Cross multiply
   105.64x = 145.72 × 83.72
4. Step 4: Simplify right side
   105.64x = 12,199.68
5. Step 5: Solve for x
   x = 12,199.68/105.64
6. Step 6: Final answer
   x = 115.48