Finding the Fourth Proportional to 12,990.64, 17,928.72 and 8,518.12

Step by Step Solution

1. Step 1: Write the proportion equation
   12,990.64 : 17,928.72 = 8,518.12 : x
2. Step 2: Convert to fraction form
   12,990.64/17,928.72 = 8,518.12/x
3. Step 3: Cross multiply
   12,990.64x = 17,928.72 × 8,518.12
4. Step 4: Simplify right side
   12,990.64x = 152,718,988.41
5. Step 5: Solve for x
   x = 152,718,988.41/12,990.64
6. Step 6: Final answer
   x = 11,756.08