Finding the Fourth Proportional to 1,222.89, 1,685.39 and 890.79

Step by Step Solution

1. Step 1: Write the proportion equation
   1,222.89 : 1,685.39 = 890.79 : x
2. Step 2: Convert to fraction form
   1,222.89/1,685.39 = 890.79/x
3. Step 3: Cross multiply
   1,222.89x = 1,685.39 × 890.79
4. Step 4: Simplify right side
   1,222.89x = 1,501,324.10
5. Step 5: Solve for x
   x = 1,501,324.10/1,222.89
6. Step 6: Final answer
   x = 1,227.69