Finding the Fourth Proportional to 1,998.72, 2,759.46 and 1,290.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,998.72 : 2,759.46 = 1,290.78 : x
2. Step 2: Convert to fraction form
   1,998.72/2,759.46 = 1,290.78/x
3. Step 3: Cross multiply
   1,998.72x = 2,759.46 × 1,290.78
4. Step 4: Simplify right side
   1,998.72x = 3,561,855.78
5. Step 5: Solve for x
   x = 3,561,855.78/1,998.72
6. Step 6: Final answer
   x = 1,782.07