Finding the Fourth Proportional to 1,990.78, 2,747.73 and 1,290.94

Step by Step Solution

1. Step 1: Write the proportion equation
   1,990.78 : 2,747.73 = 1,290.94 : x
2. Step 2: Convert to fraction form
   1,990.78/2,747.73 = 1,290.94/x
3. Step 3: Cross multiply
   1,990.78x = 2,747.73 × 1,290.94
4. Step 4: Simplify right side
   1,990.78x = 3,547,154.57
5. Step 5: Solve for x
   x = 3,547,154.57/1,990.78
6. Step 6: Final answer
   x = 1,781.79