T -test - t-table

Population standard deviation is not  given & n >≠ 30.

Point Estimate +- Margin of error 

x̄ +- z  α/2 (σ/ √ n )

t = degree of freedom= n-1

Upper Bound -   x̄ + t  α/2 (s/ √ n ) = t table(Answer)

Lower Bound -   x̄  -  t  α/2 (s / √ n )=t table(Answer)

 (s / √ n ) is Standard error