Finding the Fourth Proportional to 109.15, 150.55 and 72.31

Step by Step Solution

1. Step 1: Write the proportion equation
   109.15 : 150.55 = 72.31 : x
2. Step 2: Convert to fraction form
   109.15/150.55 = 72.31/x
3. Step 3: Cross multiply
   109.15x = 150.55 × 72.31
4. Step 4: Simplify right side
   109.15x = 10,886.27
5. Step 5: Solve for x
   x = 10,886.27/109.15
6. Step 6: Final answer
   x = 99.74