Finding the Fourth Proportional to 103.72, 142.94 and 90.58

Step by Step Solution

1. Step 1: Write the proportion equation
   103.72 : 142.94 = 90.58 : x
2. Step 2: Convert to fraction form
   103.72/142.94 = 90.58/x
3. Step 3: Cross multiply
   103.72x = 142.94 × 90.58
4. Step 4: Simplify right side
   103.72x = 12,947.51
5. Step 5: Solve for x
   x = 12,947.51/103.72
6. Step 6: Final answer
   x = 124.83