Finding the Fourth Proportional to 2,561.91, 3,843.15 and 918.60

Step by Step Solution

1. Step 1: Write the proportion equation
   2,561.91 : 3,843.15 = 918.60 : x
2. Step 2: Convert to fraction form
   2,561.91/3,843.15 = 918.60/x
3. Step 3: Cross multiply
   2,561.91x = 3,843.15 × 918.60
4. Step 4: Simplify right side
   2,561.91x = 3,530,317.59
5. Step 5: Solve for x
   x = 3,530,317.59/2,561.91
6. Step 6: Final answer
   x = 1,378.00