Finding the Fourth Proportional to 21,616.64, 32,405.72 and 8,478.40

Step by Step Solution

1. Step 1: Write the proportion equation
   21,616.64 : 32,405.72 = 8,478.40 : x
2. Step 2: Convert to fraction form
   21,616.64/32,405.72 = 8,478.40/x
3. Step 3: Cross multiply
   21,616.64x = 32,405.72 × 8,478.40
4. Step 4: Simplify right side
   21,616.64x = 274,748,656.45
5. Step 5: Solve for x
   x = 274,748,656.45/21,616.64
6. Step 6: Final answer
   x = 12,710.05