Finding the Fourth Proportional to 2,124.02, 3,185.20 and 642.78

Step by Step Solution

1. Step 1: Write the proportion equation
   2,124.02 : 3,185.20 = 642.78 : x
2. Step 2: Convert to fraction form
   2,124.02/3,185.20 = 642.78/x
3. Step 3: Cross multiply
   2,124.02x = 3,185.20 × 642.78
4. Step 4: Simplify right side
   2,124.02x = 2,047,382.86
5. Step 5: Solve for x
   x = 2,047,382.86/2,124.02
6. Step 6: Final answer
   x = 963.92