Finding the Fourth Proportional to 11.39, 15.71 and 10.91

Step by Step Solution

1. Step 1: Write the proportion equation
   11.39 : 15.71 = 10.91 : x
2. Step 2: Convert to fraction form
   11.39/15.71 = 10.91/x
3. Step 3: Cross multiply
   11.39x = 15.71 × 10.91
4. Step 4: Simplify right side
   11.39x = 171.41
5. Step 5: Solve for x
   x = 171.41/11.39
6. Step 6: Final answer
   x = 15.05