Finding the Fourth Proportional to 2,109.90, 3,163.59 and 648.78

Step by Step Solution

1. Step 1: Write the proportion equation
   2,109.90 : 3,163.59 = 648.78 : x
2. Step 2: Convert to fraction form
   2,109.90/3,163.59 = 648.78/x
3. Step 3: Cross multiply
   2,109.90x = 3,163.59 × 648.78
4. Step 4: Simplify right side
   2,109.90x = 2,052,473.92
5. Step 5: Solve for x
   x = 2,052,473.92/2,109.90
6. Step 6: Final answer
   x = 972.78