Finding the Fourth Proportional to 2,611.78, 3,915.15 and 1,309.30

Step by Step Solution

1. Step 1: Write the proportion equation
   2,611.78 : 3,915.15 = 1,309.30 : x
2. Step 2: Convert to fraction form
   2,611.78/3,915.15 = 1,309.30/x
3. Step 3: Cross multiply
   2,611.78x = 3,915.15 × 1,309.30
4. Step 4: Simplify right side
   2,611.78x = 5,126,105.90
5. Step 5: Solve for x
   x = 5,126,105.90/2,611.78
6. Step 6: Final answer
   x = 1,962.69