Finding the Fourth Proportional to 11.10, 15.31 and 7.86

Step by Step Solution

1. Step 1: Write the proportion equation
   11.10 : 15.31 = 7.86 : x
2. Step 2: Convert to fraction form
   11.10/15.31 = 7.86/x
3. Step 3: Cross multiply
   11.10x = 15.31 × 7.86
4. Step 4: Simplify right side
   11.10x = 120.34
5. Step 5: Solve for x
   x = 120.34/11.10
6. Step 6: Final answer
   x = 10.84