Finding the Fourth Proportional to 5,641.40, 7,782.72 and 3,869.90

Step by Step Solution

1. Step 1: Write the proportion equation
   5,641.40 : 7,782.72 = 3,869.90 : x
2. Step 2: Convert to fraction form
   5,641.40/7,782.72 = 3,869.90/x
3. Step 3: Cross multiply
   5,641.40x = 7,782.72 × 3,869.90
4. Step 4: Simplify right side
   5,641.40x = 30,118,348.13
5. Step 5: Solve for x
   x = 30,118,348.13/5,641.40
6. Step 6: Final answer
   x = 5,338.81