Finding the Fourth Proportional to 42,903.20, 64,351.20 and 13,320.56

Step by Step Solution

1. Step 1: Write the proportion equation
   42,903.20 : 64,351.20 = 13,320.56 : x
2. Step 2: Convert to fraction form
   42,903.20/64,351.20 = 13,320.56/x
3. Step 3: Cross multiply
   42,903.20x = 64,351.20 × 13,320.56
4. Step 4: Simplify right side
   42,903.20x = 857,194,020.67
5. Step 5: Solve for x
   x = 857,194,020.67/42,903.20
6. Step 6: Final answer
   x = 19,979.72