Finding the Fourth Proportional to 1,172.77, 1,618.42 and 648.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,172.77 : 1,618.42 = 648.80 : x
2. Step 2: Convert to fraction form
   1,172.77/1,618.42 = 648.80/x
3. Step 3: Cross multiply
   1,172.77x = 1,618.42 × 648.80
4. Step 4: Simplify right side
   1,172.77x = 1,050,033.32
5. Step 5: Solve for x
   x = 1,050,033.32/1,172.77
6. Step 6: Final answer
   x = 895.35