Finding the Fourth Proportional to 2,290.72, 3,161.20 and 1,242.78

Step by Step Solution

1. Step 1: Write the proportion equation
   2,290.72 : 3,161.20 = 1,242.78 : x
2. Step 2: Convert to fraction form
   2,290.72/3,161.20 = 1,242.78/x
3. Step 3: Cross multiply
   2,290.72x = 3,161.20 × 1,242.78
4. Step 4: Simplify right side
   2,290.72x = 3,928,676.14
5. Step 5: Solve for x
   x = 3,928,676.14/2,290.72
6. Step 6: Final answer
   x = 1,715.04