Finding the Fourth Proportional to 1,216.68, 1,678.92 and 774.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,216.68 : 1,678.92 = 774.72 : x
2. Step 2: Convert to fraction form
   1,216.68/1,678.92 = 774.72/x
3. Step 3: Cross multiply
   1,216.68x = 1,678.92 × 774.72
4. Step 4: Simplify right side
   1,216.68x = 1,300,692.90
5. Step 5: Solve for x
   x = 1,300,692.90/1,216.68
6. Step 6: Final answer
   x = 1,069.05