Respuesta :
Answer:
There is enough evidence to support the claim that students in the California state university system take significantly longer to graduate than students enrolled in private universities (P-value = 0.0007).
Step-by-step explanation:
This is a hypothesis test for the difference between populations means.
The claim is that students in the California state university system take significantly longer to graduate than students enrolled in private universities.
Then, the null and alternative hypothesis are:
[tex]H_0: \mu_1-\mu_2=0\\\\H_a:\mu_1-\mu_2> 0[/tex]
The significance level is α=0.05.
The sample standard deviation is take into account and performed a two sample t-test. The 100 students are considered to be divided equally between state and private.
The sample 1 (state), of size n1=50 has a mean of 4.5 and a standard deviation of 0.8.
The sample 2 (private), of size n2=50 has a mean of 4.1 and a standard deviation of 0.3.
The difference between sample means is Md=0.4.
[tex]M_d=M_1-M_2=4.5-4.1=0.4[/tex]
The estimated standard error of the difference between means is computed using the formula:
[tex]s_{M_d}=\sqrt{\dfrac{\sigma_1^2+\sigma_2^2}{n}}=\sqrt{\dfrac{0.8^2+0.3^2}{50}}\\\\\\s_{M_d}=\sqrt{\dfrac{0.73}{50}}=\sqrt{0.015}=0.121[/tex]
Then, we can calculate the t-statistic as:
[tex]t=\dfrac{M_d-(\mu_1-\mu_2)}{s_{M_d}}=\dfrac{0.4-0}{0.121}=\dfrac{0.4}{0.121}=3.3104[/tex]
The degrees of freedom for this test are:
[tex]df=n_1+n_2-1=50+50-2=98[/tex]
This test is a right-tailed test, with 98 degrees of freedom and t=3.3104, so the P-value for this test is calculated as (using a t-table):
[tex]\text{P-value}=P(t>3.3104)=0.0007[/tex]
As the P-value (0.0007) is smaller than the significance level (0.05), the effect is significant.
The null hypothesis is rejected.
There is enough evidence to support the claim that students in the California state university system take significantly longer to graduate than students enrolled in private universities.
