Finding the Fourth Proportional to 2,099.80, 2,899.56 and 1,315.20

Step by Step Solution

1. Step 1: Write the proportion equation
   2,099.80 : 2,899.56 = 1,315.20 : x
2. Step 2: Convert to fraction form
   2,099.80/2,899.56 = 1,315.20/x
3. Step 3: Cross multiply
   2,099.80x = 2,899.56 × 1,315.20
4. Step 4: Simplify right side
   2,099.80x = 3,813,501.31
5. Step 5: Solve for x
   x = 3,813,501.31/2,099.80
6. Step 6: Final answer
   x = 1,816.13