Finding the Fourth Proportional to 21,128.72, 31,700.10 and 7,090.12

Step by Step Solution

1. Step 1: Write the proportion equation
   21,128.72 : 31,700.10 = 7,090.12 : x
2. Step 2: Convert to fraction form
   21,128.72/31,700.10 = 7,090.12/x
3. Step 3: Cross multiply
   21,128.72x = 31,700.10 × 7,090.12
4. Step 4: Simplify right side
   21,128.72x = 224,757,513.01
5. Step 5: Solve for x
   x = 224,757,513.01/21,128.72
6. Step 6: Final answer
   x = 10,637.54