Finding the Fourth Proportional to 2,109.80, 2,904.60 and 2,005.90

Step by Step Solution

1. Step 1: Write the proportion equation
   2,109.80 : 2,904.60 = 2,005.90 : x
2. Step 2: Convert to fraction form
   2,109.80/2,904.60 = 2,005.90/x
3. Step 3: Cross multiply
   2,109.80x = 2,904.60 × 2,005.90
4. Step 4: Simplify right side
   2,109.80x = 5,826,337.14
5. Step 5: Solve for x
   x = 5,826,337.14/2,109.80
6. Step 6: Final answer
   x = 2,761.56