Finding the Fourth Proportional to 2,167.80, 2,991.56 and 1,223.79

Step by Step Solution

1. Step 1: Write the proportion equation
   2,167.80 : 2,991.56 = 1,223.79 : x
2. Step 2: Convert to fraction form
   2,167.80/2,991.56 = 1,223.79/x
3. Step 3: Cross multiply
   2,167.80x = 2,991.56 × 1,223.79
4. Step 4: Simplify right side
   2,167.80x = 3,661,023.88
5. Step 5: Solve for x
   x = 3,661,023.88/2,167.80
6. Step 6: Final answer
   x = 1,688.82