Finding the Fourth Proportional to 1,020.72, 1,408.53 and 578.76

Step by Step Solution

1. Step 1: Write the proportion equation
   1,020.72 : 1,408.53 = 578.76 : x
2. Step 2: Convert to fraction form
   1,020.72/1,408.53 = 578.76/x
3. Step 3: Cross multiply
   1,020.72x = 1,408.53 × 578.76
4. Step 4: Simplify right side
   1,020.72x = 815,200.82
5. Step 5: Solve for x
   x = 815,200.82/1,020.72
6. Step 6: Final answer
   x = 798.65