Finding the Fourth Proportional to 1,408.78, 2,113.98 and 679.24

Step by Step Solution

1. Step 1: Write the proportion equation
   1,408.78 : 2,113.98 = 679.24 : x
2. Step 2: Convert to fraction form
   1,408.78/2,113.98 = 679.24/x
3. Step 3: Cross multiply
   1,408.78x = 2,113.98 × 679.24
4. Step 4: Simplify right side
   1,408.78x = 1,435,899.78
5. Step 5: Solve for x
   x = 1,435,899.78/1,408.78
6. Step 6: Final answer
   x = 1,019.25