Finding the Fourth Proportional to 1,491.99, 2,238.89 and 518.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,491.99 : 2,238.89 = 518.78 : x
2. Step 2: Convert to fraction form
   1,491.99/2,238.89 = 518.78/x
3. Step 3: Cross multiply
   1,491.99x = 2,238.89 × 518.78
4. Step 4: Simplify right side
   1,491.99x = 1,161,477.57
5. Step 5: Solve for x
   x = 1,161,477.57/1,491.99
6. Step 6: Final answer
   x = 778.48