Finding the Fourth Proportional to 2,561.72, 3,840.15 and 1,261.67

Step by Step Solution

1. Step 1: Write the proportion equation
   2,561.72 : 3,840.15 = 1,261.67 : x
2. Step 2: Convert to fraction form
   2,561.72/3,840.15 = 1,261.67/x
3. Step 3: Cross multiply
   2,561.72x = 3,840.15 × 1,261.67
4. Step 4: Simplify right side
   2,561.72x = 4,845,002.05
5. Step 5: Solve for x
   x = 4,845,002.05/2,561.72
6. Step 6: Final answer
   x = 1,891.31