Finding the Fourth Proportional to 1,222.18, 1,685.98 and 779.61

Step by Step Solution

1. Step 1: Write the proportion equation
   1,222.18 : 1,685.98 = 779.61 : x
2. Step 2: Convert to fraction form
   1,222.18/1,685.98 = 779.61/x
3. Step 3: Cross multiply
   1,222.18x = 1,685.98 × 779.61
4. Step 4: Simplify right side
   1,222.18x = 1,314,406.87
5. Step 5: Solve for x
   x = 1,314,406.87/1,222.18
6. Step 6: Final answer
   x = 1,075.46