Finding the Fourth Proportional to 12,636, 17,439.72 and 8,172.84

Step by Step Solution

1. Step 1: Write the proportion equation
   12,636 : 17,439.72 = 8,172.84 : x
2. Step 2: Convert to fraction form
   12,636/17,439.72 = 8,172.84/x
3. Step 3: Cross multiply
   12,636x = 17,439.72 × 8,172.84
4. Step 4: Simplify right side
   12,636x = 142,532,041.20
5. Step 5: Solve for x
   x = 142,532,041.20/12,636
6. Step 6: Final answer
   x = 11,279.84