Finding the Third Proportional to 9,640 and 12,840

Step by Step Solution

1. Step 1: Write the proportion equation
   9,640 : 12,840 = 12,840 : x
2. Step 2: Convert to fraction form
   9,640/12,840 = 12,840/x
3. Step 3: Cross multiply
   9,640x = 12,840 × 12,840
4. Step 4: Simplify right side
   9,640x = 164,865,600
5. Step 5: Solve for x
   x = 164,865,600/9,640
6. Step 6: Final answer
   x = 17,102.24