Finding the Fourth Proportional to 11.10, 15.39 and 10.91

Step by Step Solution

1. Step 1: Write the proportion equation
   11.10 : 15.39 = 10.91 : x
2. Step 2: Convert to fraction form
   11.10/15.39 = 10.91/x
3. Step 3: Cross multiply
   11.10x = 15.39 × 10.91
4. Step 4: Simplify right side
   11.10x = 167.94
5. Step 5: Solve for x
   x = 167.94/11.10
6. Step 6: Final answer
   x = 15.12