Finding the Fourth Proportional to 2,167.78, 2,991.31 and 1,223.49

Step by Step Solution

1. Step 1: Write the proportion equation
   2,167.78 : 2,991.31 = 1,223.49 : x
2. Step 2: Convert to fraction form
   2,167.78/2,991.31 = 1,223.49/x
3. Step 3: Cross multiply
   2,167.78x = 2,991.31 × 1,223.49
4. Step 4: Simplify right side
   2,167.78x = 3,659,837.87
5. Step 5: Solve for x
   x = 3,659,837.87/2,167.78
6. Step 6: Final answer
   x = 1,688.29