Finding the Fourth Proportional to 21,156.42, 31,738.64 and 8,507.15

Step by Step Solution

1. Step 1: Write the proportion equation
   21,156.42 : 31,738.64 = 8,507.15 : x
2. Step 2: Convert to fraction form
   21,156.42/31,738.64 = 8,507.15/x
3. Step 3: Cross multiply
   21,156.42x = 31,738.64 × 8,507.15
4. Step 4: Simplify right side
   21,156.42x = 270,005,378.33
5. Step 5: Solve for x
   x = 270,005,378.33/21,156.42
6. Step 6: Final answer
   x = 12,762.34