Finding the Fourth Proportional to 1,216.34, 1,678.28 and 774.89

Step by Step Solution

1. Step 1: Write the proportion equation
   1,216.34 : 1,678.28 = 774.89 : x
2. Step 2: Convert to fraction form
   1,216.34/1,678.28 = 774.89/x
3. Step 3: Cross multiply
   1,216.34x = 1,678.28 × 774.89
4. Step 4: Simplify right side
   1,216.34x = 1,300,470.12
5. Step 5: Solve for x
   x = 1,300,470.12/1,216.34
6. Step 6: Final answer
   x = 1,069.17