Finding the Fourth Proportional to 13,215.63, 19,784.60 and 8,521.78

Step by Step Solution

1. Step 1: Write the proportion equation
   13,215.63 : 19,784.60 = 8,521.78 : x
2. Step 2: Convert to fraction form
   13,215.63/19,784.60 = 8,521.78/x
3. Step 3: Cross multiply
   13,215.63x = 19,784.60 × 8,521.78
4. Step 4: Simplify right side
   13,215.63x = 168,600,089.15
5. Step 5: Solve for x
   x = 168,600,089.15/13,215.63
6. Step 6: Final answer
   x = 12,757.63