Finding the Fourth Proportional to 1,679.72, 2,517.78 and 812.84

Step by Step Solution

1. Step 1: Write the proportion equation
   1,679.72 : 2,517.78 = 812.84 : x
2. Step 2: Convert to fraction form
   1,679.72/2,517.78 = 812.84/x
3. Step 3: Cross multiply
   1,679.72x = 2,517.78 × 812.84
4. Step 4: Simplify right side
   1,679.72x = 2,046,552.30
5. Step 5: Solve for x
   x = 2,046,552.30/1,679.72
6. Step 6: Final answer
   x = 1,218.39