Finding the Fourth Proportional to 12,756.30, 19,131.69 and 3,990.07

Step by Step Solution

1. Step 1: Write the proportion equation
   12,756.30 : 19,131.69 = 3,990.07 : x
2. Step 2: Convert to fraction form
   12,756.30/19,131.69 = 3,990.07/x
3. Step 3: Cross multiply
   12,756.30x = 19,131.69 × 3,990.07
4. Step 4: Simplify right side
   12,756.30x = 76,336,782.32
5. Step 5: Solve for x
   x = 76,336,782.32/12,756.30
6. Step 6: Final answer
   x = 5,984.24