# For a symmetrical distribution approximately 68% of the cases are ?

1. X¯¯¯¯3SX¯−3S and X¯¯¯¯+3S
2. X¯¯¯¯2SX¯−2S and X¯¯¯¯+2S
3. X¯¯¯¯SX¯−S and X¯¯¯¯+S
4. None of these