Finding the Fourth Proportional to 105.30, 145.38 and 83.40

Step by Step Solution

1. Step 1: Write the proportion equation
   105.30 : 145.38 = 83.40 : x
2. Step 2: Convert to fraction form
   105.30/145.38 = 83.40/x
3. Step 3: Cross multiply
   105.30x = 145.38 × 83.40
4. Step 4: Simplify right side
   105.30x = 12,124.69
5. Step 5: Solve for x
   x = 12,124.69/105.30
6. Step 6: Final answer
   x = 115.14