Finding the Fourth Proportional to 15,929.52, 21,978.72 and 9,640.68

Step by Step Solution

1. Step 1: Write the proportion equation
   15,929.52 : 21,978.72 = 9,640.68 : x
2. Step 2: Convert to fraction form
   15,929.52/21,978.72 = 9,640.68/x
3. Step 3: Cross multiply
   15,929.52x = 21,978.72 × 9,640.68
4. Step 4: Simplify right side
   15,929.52x = 211,889,806.33
5. Step 5: Solve for x
   x = 211,889,806.33/15,929.52
6. Step 6: Final answer
   x = 13,301.71