Finding the Fourth Proportional to 21,131.70, 31,679.71 and 13,323.30

Step by Step Solution

1. Step 1: Write the proportion equation
   21,131.70 : 31,679.71 = 13,323.30 : x
2. Step 2: Convert to fraction form
   21,131.70/31,679.71 = 13,323.30/x
3. Step 3: Cross multiply
   21,131.70x = 31,679.71 × 13,323.30
4. Step 4: Simplify right side
   21,131.70x = 422,078,280.24
5. Step 5: Solve for x
   x = 422,078,280.24/21,131.70
6. Step 6: Final answer
   x = 19,973.70