Finding the Fourth Proportional to 21,150.64, 31,724.79 and 7,109.21

Step by Step Solution

1. Step 1: Write the proportion equation
   21,150.64 : 31,724.79 = 7,109.21 : x
2. Step 2: Convert to fraction form
   21,150.64/31,724.79 = 7,109.21/x
3. Step 3: Cross multiply
   21,150.64x = 31,724.79 × 7,109.21
4. Step 4: Simplify right side
   21,150.64x = 225,538,194.32
5. Step 5: Solve for x
   x = 225,538,194.32/21,150.64
6. Step 6: Final answer
   x = 10,663.42