Finding the Fourth Proportional to 21,212, 31,812.74 and 7,171.72

Step by Step Solution

1. Step 1: Write the proportion equation
   21,212 : 31,812.74 = 7,171.72 : x
2. Step 2: Convert to fraction form
   21,212/31,812.74 = 7,171.72/x
3. Step 3: Cross multiply
   21,212x = 31,812.74 × 7,171.72
4. Step 4: Simplify right side
   21,212x = 228,152,063.71
5. Step 5: Solve for x
   x = 228,152,063.71/21,212
6. Step 6: Final answer
   x = 10,755.80