Finding the Fourth Proportional to 21,256.64, 31,878.20 and 7,021.96

Step by Step Solution

1. Step 1: Write the proportion equation
   21,256.64 : 31,878.20 = 7,021.96 : x
2. Step 2: Convert to fraction form
   21,256.64/31,878.20 = 7,021.96/x
3. Step 3: Cross multiply
   21,256.64x = 31,878.20 × 7,021.96
4. Step 4: Simplify right side
   21,256.64x = 223,847,445.27
5. Step 5: Solve for x
   x = 223,847,445.27/21,256.64
6. Step 6: Final answer
   x = 10,530.71