Finding the Fourth Proportional to 21,913.72, 30,243.05 and 12,964.10

Step by Step Solution

1. Step 1: Write the proportion equation
   21,913.72 : 30,243.05 = 12,964.10 : x
2. Step 2: Convert to fraction form
   21,913.72/30,243.05 = 12,964.10/x
3. Step 3: Cross multiply
   21,913.72x = 30,243.05 × 12,964.10
4. Step 4: Simplify right side
   21,913.72x = 392,073,924.51
5. Step 5: Solve for x
   x = 392,073,924.51/21,913.72
6. Step 6: Final answer
   x = 17,891.71