Finding the Fourth Proportional to 21,130.51, 31,632.63 and 12,785.31

Step by Step Solution

1. Step 1: Write the proportion equation
   21,130.51 : 31,632.63 = 12,785.31 : x
2. Step 2: Convert to fraction form
   21,130.51/31,632.63 = 12,785.31/x
3. Step 3: Cross multiply
   21,130.51x = 31,632.63 × 12,785.31
4. Step 4: Simplify right side
   21,130.51x = 404,432,980.67
5. Step 5: Solve for x
   x = 404,432,980.67/21,130.51
6. Step 6: Final answer
   x = 19,139.76