Finding the Fourth Proportional to 12,899.64, 19,351.89 and 3,665.64

Step by Step Solution

1. Step 1: Write the proportion equation
   12,899.64 : 19,351.89 = 3,665.64 : x
2. Step 2: Convert to fraction form
   12,899.64/19,351.89 = 3,665.64/x
3. Step 3: Cross multiply
   12,899.64x = 19,351.89 × 3,665.64
4. Step 4: Simplify right side
   12,899.64x = 70,937,062.06
5. Step 5: Solve for x
   x = 70,937,062.06/12,899.64
6. Step 6: Final answer
   x = 5,499.15