Finding the Third Proportional to 15,915 and 21,240

Step by Step Solution

1. Step 1: Write the proportion equation
   15,915 : 21,240 = 21,240 : x
2. Step 2: Convert to fraction form
   15,915/21,240 = 21,240/x
3. Step 3: Cross multiply
   15,915x = 21,240 × 21,240
4. Step 4: Simplify right side
   15,915x = 451,137,600
5. Step 5: Solve for x
   x = 451,137,600/15,915
6. Step 6: Final answer
   x = 28,346.69