Finding the Fourth Proportional to 11.91, 17.86 and 3.89

Step by Step Solution

1. Step 1: Write the proportion equation
   11.91 : 17.86 = 3.89 : x
2. Step 2: Convert to fraction form
   11.91/17.86 = 3.89/x
3. Step 3: Cross multiply
   11.91x = 17.86 × 3.89
4. Step 4: Simplify right side
   11.91x = 69.51
5. Step 5: Solve for x
   x = 69.51/11.91
6. Step 6: Final answer
   x = 5.84