Finding the Fourth Proportional to 15,499.79, 21,388.80 and 8,426.15

Step by Step Solution

1. Step 1: Write the proportion equation
   15,499.79 : 21,388.80 = 8,426.15 : x
2. Step 2: Convert to fraction form
   15,499.79/21,388.80 = 8,426.15/x
3. Step 3: Cross multiply
   15,499.79x = 21,388.80 × 8,426.15
4. Step 4: Simplify right side
   15,499.79x = 180,225,088.05
5. Step 5: Solve for x
   x = 180,225,088.05/15,499.79
6. Step 6: Final answer
   x = 11,627.59