Finding the Fourth Proportional to 21,139.94, 31,708.04 and 12,817.50

Step by Step Solution

1. Step 1: Write the proportion equation
   21,139.94 : 31,708.04 = 12,817.50 : x
2. Step 2: Convert to fraction form
   21,139.94/31,708.04 = 12,817.50/x
3. Step 3: Cross multiply
   21,139.94x = 31,708.04 × 12,817.50
4. Step 4: Simplify right side
   21,139.94x = 406,417,802.70
5. Step 5: Solve for x
   x = 406,417,802.70/21,139.94
6. Step 6: Final answer
   x = 19,225.12