Finding the Fourth Proportional to 1,143.86, 1,578.51 and 619.88

Step by Step Solution

1. Step 1: Write the proportion equation
   1,143.86 : 1,578.51 = 619.88 : x
2. Step 2: Convert to fraction form
   1,143.86/1,578.51 = 619.88/x
3. Step 3: Cross multiply
   1,143.86x = 1,578.51 × 619.88
4. Step 4: Simplify right side
   1,143.86x = 978,478.89
5. Step 5: Solve for x
   x = 978,478.89/1,143.86
6. Step 6: Final answer
   x = 855.42