Finding the Fourth Proportional to 2,211.30, 3,315.83 and 1,287.05

Step by Step Solution

1. Step 1: Write the proportion equation
   2,211.30 : 3,315.83 = 1,287.05 : x
2. Step 2: Convert to fraction form
   2,211.30/3,315.83 = 1,287.05/x
3. Step 3: Cross multiply
   2,211.30x = 3,315.83 × 1,287.05
4. Step 4: Simplify right side
   2,211.30x = 4,267,615.99
5. Step 5: Solve for x
   x = 4,267,615.99/2,211.30
6. Step 6: Final answer
   x = 1,929.91