Finding the Fourth Proportional to 2,155.28, 2,973.96 and 1,223.76

Step by Step Solution

1. Step 1: Write the proportion equation
   2,155.28 : 2,973.96 = 1,223.76 : x
2. Step 2: Convert to fraction form
   2,155.28/2,973.96 = 1,223.76/x
3. Step 3: Cross multiply
   2,155.28x = 2,973.96 × 1,223.76
4. Step 4: Simplify right side
   2,155.28x = 3,639,413.29
5. Step 5: Solve for x
   x = 3,639,413.29/2,155.28
6. Step 6: Final answer
   x = 1,688.60