Finding the Fourth Proportional to 3,991.56, 5,978.63 and 3,290.35

Step by Step Solution

1. Step 1: Write the proportion equation
   3,991.56 : 5,978.63 = 3,290.35 : x
2. Step 2: Convert to fraction form
   3,991.56/5,978.63 = 3,290.35/x
3. Step 3: Cross multiply
   3,991.56x = 5,978.63 × 3,290.35
4. Step 4: Simplify right side
   3,991.56x = 19,671,788.75
5. Step 5: Solve for x
   x = 19,671,788.75/3,991.56
6. Step 6: Final answer
   x = 4,928.35