Finding the Fourth Proportional to 12,686.70, 17,507.34 and 7,021.29

Step by Step Solution

1. Step 1: Write the proportion equation
   12,686.70 : 17,507.34 = 7,021.29 : x
2. Step 2: Convert to fraction form
   12,686.70/17,507.34 = 7,021.29/x
3. Step 3: Cross multiply
   12,686.70x = 17,507.34 × 7,021.29
4. Step 4: Simplify right side
   12,686.70x = 122,924,111.27
5. Step 5: Solve for x
   x = 122,924,111.27/12,686.70
6. Step 6: Final answer
   x = 9,689.21