Finding the Fourth Proportional to 7,086.81, 9,779.55 and 3,900.09

Step by Step Solution

1. Step 1: Write the proportion equation
   7,086.81 : 9,779.55 = 3,900.09 : x
2. Step 2: Convert to fraction form
   7,086.81/9,779.55 = 3,900.09/x
3. Step 3: Cross multiply
   7,086.81x = 9,779.55 × 3,900.09
4. Step 4: Simplify right side
   7,086.81x = 38,141,125.16
5. Step 5: Solve for x
   x = 38,141,125.16/7,086.81
6. Step 6: Final answer
   x = 5,381.99