1 P z 166 2 for a t distribution with n 20 how many df ar

1)

P( z < 1.66) =

2)

for a t distribution with n = 20 how many df are?

Solution

1)

looking in the tables of normal distribution ( standard variable) we have

P( z > 1.66) = 0.0485

P( z < 1.66) = 1 - 0.0485 = 0.9515

2)

as we know df = n-1 for a t distribution

so

df = 19