Finding the Fourth Proportional to 91.47, 137.15 and 72.15

Step by Step Solution

1. Step 1: Write the proportion equation
   91.47 : 137.15 = 72.15 : x
2. Step 2: Convert to fraction form
   91.47/137.15 = 72.15/x
3. Step 3: Cross multiply
   91.47x = 137.15 × 72.15
4. Step 4: Simplify right side
   91.47x = 9,895.54
5. Step 5: Solve for x
   x = 9,895.54/91.47
6. Step 6: Final answer
   x = 108.19