Finding the Fourth Proportional to 1,012.78, 1,521.60 and 648.28

Step by Step Solution

1. Step 1: Write the proportion equation
   1,012.78 : 1,521.60 = 648.28 : x
2. Step 2: Convert to fraction form
   1,012.78/1,521.60 = 648.28/x
3. Step 3: Cross multiply
   1,012.78x = 1,521.60 × 648.28
4. Step 4: Simplify right side
   1,012.78x = 986,422.85
5. Step 5: Solve for x
   x = 986,422.85/1,012.78
6. Step 6: Final answer
   x = 973.98