Answer:
Step 1 t = - 2.552
Step 2 t = 1.356
Step 3 two values t = - 2.12 on the left and t = 2.12 on the right
Step-by-step explanation:
Normal Distribution
size sample < 30
Table to use t-student table
a) left-tailed test α = 0,01 n = 19 gl = 19 -1 gl = 18
Directly from t table
t = - 2.552
b) Right-tailed test α = 0,1 n = 13 gl = 13 - 1 gl =12
Directly from t table
t = 1.356
c) Two-tailed test α = 0,05 but two tails means we use α/2
α/2 = 0,025 n = 17 gl = n - 1 gl = 17 -1 gl = 16
From table:
t = - 2.12 on the left tail and t = 2.12 on the right tail