In a t distribution, as the degree of freedom reaches infinity, the size of the 1% and 5% values of the t are the same as that for z. That is, it reaches 1.96 for 95% critical values and 1.64 for 90% critical values.
The two intervals do not seem to have a significant difference between them.
Since this is a weight reduction study, we did a one-directional t test. Results showed that the diet resulted in a significant decrease in weight, both for a 90% and 95% confidence level.
In both cases, it is reasonable to say that two-thirds of the general population agrees with the principle of University top-up fees. The hypothesized p is included in both intervals. We, therefore, do not reject the null hypothesis.