Finding the Fourth Proportional to 103.67, 142.71 and 90.72

Step by Step Solution

1. Step 1: Write the proportion equation
   103.67 : 142.71 = 90.72 : x
2. Step 2: Convert to fraction form
   103.67/142.71 = 90.72/x
3. Step 3: Cross multiply
   103.67x = 142.71 × 90.72
4. Step 4: Simplify right side
   103.67x = 12,946.65
5. Step 5: Solve for x
   x = 12,946.65/103.67
6. Step 6: Final answer
   x = 124.89