Answer :
a.) t calc = 3.1
t-table = 1.77
Since the t-calc > t-table, we reject H0 and accep HA.
We conclude that the true average refrectometer reading is greater than 20.
b.) t-calc = 1.8
t-table = 2.82
Since t-calc < t-table, we fail to reject H0.
We conclude that the true average refrectometer reading may be 20.
t-table = 1.77
Since the t-calc > t-table, we reject H0 and accep HA.
We conclude that the true average refrectometer reading is greater than 20.
b.) t-calc = 1.8
t-table = 2.82
Since t-calc < t-table, we fail to reject H0.
We conclude that the true average refrectometer reading may be 20.