Finding the Fourth Proportional to 1,012.86, 1,397.88 and 570.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,012.86 : 1,397.88 = 570.78 : x
2. Step 2: Convert to fraction form
   1,012.86/1,397.88 = 570.78/x
3. Step 3: Cross multiply
   1,012.86x = 1,397.88 × 570.78
4. Step 4: Simplify right side
   1,012.86x = 797,881.95
5. Step 5: Solve for x
   x = 797,881.95/1,012.86
6. Step 6: Final answer
   x = 787.75