Finding the Fourth Proportional to 1,143.86, 1,578.53 and 619.89

Step by Step Solution

1. Step 1: Write the proportion equation
   1,143.86 : 1,578.53 = 619.89 : x
2. Step 2: Convert to fraction form
   1,143.86/1,578.53 = 619.89/x
3. Step 3: Cross multiply
   1,143.86x = 1,578.53 × 619.89
4. Step 4: Simplify right side
   1,143.86x = 978,514.96
5. Step 5: Solve for x
   x = 978,514.96/1,143.86
6. Step 6: Final answer
   x = 855.45