Finding the Fourth Proportional to 21,779, 30,057.74 and 12,947

Step by Step Solution

1. Step 1: Write the proportion equation
   21,779 : 30,057.74 = 12,947 : x
2. Step 2: Convert to fraction form
   21,779/30,057.74 = 12,947/x
3. Step 3: Cross multiply
   21,779x = 30,057.74 × 12,947
4. Step 4: Simplify right side
   21,779x = 389,157,559.78
5. Step 5: Solve for x
   x = 389,157,559.78/21,779
6. Step 6: Final answer
   x = 17,868.48