Finding the Fourth Proportional to 3,878.18, 5,351.90 and 2,109.78

Step by Step Solution

1. Step 1: Write the proportion equation
   3,878.18 : 5,351.90 = 2,109.78 : x
2. Step 2: Convert to fraction form
   3,878.18/5,351.90 = 2,109.78/x
3. Step 3: Cross multiply
   3,878.18x = 5,351.90 × 2,109.78
4. Step 4: Simplify right side
   3,878.18x = 11,291,321.03
5. Step 5: Solve for x
   x = 11,291,321.03/3,878.18
6. Step 6: Final answer
   x = 2,911.50