Finding the Fourth Proportional to 1,002.78, 1,384.49 and 648.81

Step by Step Solution

1. Step 1: Write the proportion equation
   1,002.78 : 1,384.49 = 648.81 : x
2. Step 2: Convert to fraction form
   1,002.78/1,384.49 = 648.81/x
3. Step 3: Cross multiply
   1,002.78x = 1,384.49 × 648.81
4. Step 4: Simplify right side
   1,002.78x = 898,272.58
5. Step 5: Solve for x
   x = 898,272.58/1,002.78
6. Step 6: Final answer
   x = 895.78