Answer:
a
The null hypothesis is [tex]H_o : \ \sigma^2 = 1.9[/tex]
The alternative hypothesis is [tex]H_a : \ \sigma^2 \ne 1.9[/tex]
b
[tex]X^2 = 13.74[/tex]
c
The decision rule is
Reject the null hypothesis
d
The conclusion is
There is no sufficient evidence to conclude that the variance of the immune response is equal to 1.9.
Step-by-step explanation:
From the question we are are told that
The variance is [tex]\sigma ^2 = 1.9[/tex]
The sample size is n = 30
The sample variance is [tex]s^2 = 0.9[/tex]
The level of significance is [tex]\alpha = 0.05[/tex]
The null hypothesis is [tex]H_o : \ \sigma^2 = 1.9[/tex]
The alternative hypothesis is [tex]H_a : \ \sigma^2 \ne 1.9[/tex]
Generally the test statistics is mathematically represented as
[tex]X^2 = \frac{ (n- 1 ) * s^2 }{ \sigma^2 }[/tex]
=> [tex]X^2 = \frac{ (30 - 1 ) * 0.9 }{1.9 }[/tex]
=> [tex]X^2 = 13.74[/tex]
Generally from the degree of freedom is mathematically represented as
[tex]df = n- 1[/tex]
=> [tex]df = 30 - 1[/tex]
=> [tex]df = 29[/tex]
Generally from the chi distribution table the critical value of [tex]\frac{\alpha}{2} \ and \ 1 - \frac{ \alpha }{2}[/tex] at a degree of freedom of [tex]df = 29[/tex] is
[tex]X^2 _{ \frac{\alpha }{2} , df } = X^2 _{ \frac{0.05 }{2} , 29 } = 45.7[/tex]
=> [tex]X^2 _{ 1 - \frac{\alpha }{2} , df } = X^2 _{1 - \frac{0.05 }{2} , 29 } = 16.0 5[/tex]
Gnerally from the values obtained we see that
[tex]X^2 < X^2 _{ 1 - \frac{\alpha }{2} , df }[/tex] hence
The decision rule is
Reject the null hypothesis
The conclusion is
There is no sufficient evidence to conclude that the variance of the immune response is equal to 1.9.
