Finding the Fourth Proportional to 1,057.79, 1,578.86 and 936.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,057.79 : 1,578.86 = 936.15 : x
2. Step 2: Convert to fraction form
   1,057.79/1,578.86 = 936.15/x
3. Step 3: Cross multiply
   1,057.79x = 1,578.86 × 936.15
4. Step 4: Simplify right side
   1,057.79x = 1,478,045.11
5. Step 5: Solve for x
   x = 1,478,045.11/1,057.79
6. Step 6: Final answer
   x = 1,397.30