Finding the Fourth Proportional to 2,109.24, 2,910.78 and 1,225.20

Step by Step Solution

1. Step 1: Write the proportion equation
   2,109.24 : 2,910.78 = 1,225.20 : x
2. Step 2: Convert to fraction form
   2,109.24/2,910.78 = 1,225.20/x
3. Step 3: Cross multiply
   2,109.24x = 2,910.78 × 1,225.20
4. Step 4: Simplify right side
   2,109.24x = 3,566,287.66
5. Step 5: Solve for x
   x = 3,566,287.66/2,109.24
6. Step 6: Final answer
   x = 1,690.79