Finding the Fourth Proportional to 103.15, 141.91 and 100.72

Step by Step Solution

1. Step 1: Write the proportion equation
   103.15 : 141.91 = 100.72 : x
2. Step 2: Convert to fraction form
   103.15/141.91 = 100.72/x
3. Step 3: Cross multiply
   103.15x = 141.91 × 100.72
4. Step 4: Simplify right side
   103.15x = 14,293.18
5. Step 5: Solve for x
   x = 14,293.18/103.15
6. Step 6: Final answer
   x = 138.57