Finding the Fourth Proportional to 3,778.85, 5,215.12 and 2,100.80

Step by Step Solution

1. Step 1: Write the proportion equation
   3,778.85 : 5,215.12 = 2,100.80 : x
2. Step 2: Convert to fraction form
   3,778.85/5,215.12 = 2,100.80/x
3. Step 3: Cross multiply
   3,778.85x = 5,215.12 × 2,100.80
4. Step 4: Simplify right side
   3,778.85x = 10,955,931.88
5. Step 5: Solve for x
   x = 10,955,931.88/3,778.85
6. Step 6: Final answer
   x = 2,899.27