Finding the Fourth Proportional to 103.42, 142.63 and 91.15

Step by Step Solution

1. Step 1: Write the proportion equation
   103.42 : 142.63 = 91.15 : x
2. Step 2: Convert to fraction form
   103.42/142.63 = 91.15/x
3. Step 3: Cross multiply
   103.42x = 142.63 × 91.15
4. Step 4: Simplify right side
   103.42x = 13,000.72
5. Step 5: Solve for x
   x = 13,000.72/103.42
6. Step 6: Final answer
   x = 125.71