Finding the Fourth Proportional to 1,398.72, 2,099.76 and 822

Step by Step Solution

1. Step 1: Write the proportion equation
   1,398.72 : 2,099.76 = 822 : x
2. Step 2: Convert to fraction form
   1,398.72/2,099.76 = 822/x
3. Step 3: Cross multiply
   1,398.72x = 2,099.76 × 822
4. Step 4: Simplify right side
   1,398.72x = 1,726,002.72
5. Step 5: Solve for x
   x = 1,726,002.72/1,398.72
6. Step 6: Final answer
   x = 1,233.99