Finding the Fourth Proportional to 1,143.72, 1,578.35 and 619.76

Step by Step Solution

1. Step 1: Write the proportion equation
   1,143.72 : 1,578.35 = 619.76 : x
2. Step 2: Convert to fraction form
   1,143.72/1,578.35 = 619.76/x
3. Step 3: Cross multiply
   1,143.72x = 1,578.35 × 619.76
4. Step 4: Simplify right side
   1,143.72x = 978,187.21
5. Step 5: Solve for x
   x = 978,187.21/1,143.72
6. Step 6: Final answer
   x = 855.27