Finding the Fourth Proportional to 11,385.48, 17,085.89 and 3,990

Step by Step Solution

1. Step 1: Write the proportion equation
   11,385.48 : 17,085.89 = 3,990 : x
2. Step 2: Convert to fraction form
   11,385.48/17,085.89 = 3,990/x
3. Step 3: Cross multiply
   11,385.48x = 17,085.89 × 3,990
4. Step 4: Simplify right side
   11,385.48x = 68,172,701.10
5. Step 5: Solve for x
   x = 68,172,701.10/11,385.48
6. Step 6: Final answer
   x = 5,987.69