Finding the Fourth Proportional to 105.78, 145.94 and 74.72

Step by Step Solution

1. Step 1: Write the proportion equation
   105.78 : 145.94 = 74.72 : x
2. Step 2: Convert to fraction form
   105.78/145.94 = 74.72/x
3. Step 3: Cross multiply
   105.78x = 145.94 × 74.72
4. Step 4: Simplify right side
   105.78x = 10,904.64
5. Step 5: Solve for x
   x = 10,904.64/105.78
6. Step 6: Final answer
   x = 103.09