Finding the Fourth Proportional to 11,781.30, 17,671.35 and 3,990.18

Step by Step Solution

1. Step 1: Write the proportion equation
   11,781.30 : 17,671.35 = 3,990.18 : x
2. Step 2: Convert to fraction form
   11,781.30/17,671.35 = 3,990.18/x
3. Step 3: Cross multiply
   11,781.30x = 17,671.35 × 3,990.18
4. Step 4: Simplify right side
   11,781.30x = 70,511,867.34
5. Step 5: Solve for x
   x = 70,511,867.34/11,781.30
6. Step 6: Final answer
   x = 5,985.07