Finding the Fourth Proportional to 1,815.68, 2,499.12 and 1,290.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,815.68 : 2,499.12 = 1,290.80 : x
2. Step 2: Convert to fraction form
   1,815.68/2,499.12 = 1,290.80/x
3. Step 3: Cross multiply
   1,815.68x = 2,499.12 × 1,290.80
4. Step 4: Simplify right side
   1,815.68x = 3,225,864.10
5. Step 5: Solve for x
   x = 3,225,864.10/1,815.68
6. Step 6: Final answer
   x = 1,776.67