Finding the Fourth Proportional to 2,608.89, 3,913.34 and 661.09

Step by Step Solution

1. Step 1: Write the proportion equation
   2,608.89 : 3,913.34 = 661.09 : x
2. Step 2: Convert to fraction form
   2,608.89/3,913.34 = 661.09/x
3. Step 3: Cross multiply
   2,608.89x = 3,913.34 × 661.09
4. Step 4: Simplify right side
   2,608.89x = 2,587,047.07
5. Step 5: Solve for x
   x = 2,587,047.07/2,608.89
6. Step 6: Final answer
   x = 991.63