Answer: 15.08
Explanation:
The test statistic for difference between two population means is given by :-
![z=\frac{\overline{X}-\overline{Y}}{\sqrt{(\sigma_x^2)/(n_x)+(\sigma_y^2)/(n_y)}}](https://img.qammunity.org/2020/formulas/mathematics/college/6n86lwze7u3e2zyi56ky4cy8a88ipu97av.png)
Given : State A State B
Sample size 80 50
Mean interest rate (%) 4.0 4.5
Population variance 0.04 0.03
Then , the test statistic for difference between two population means will be :-
![z=\frac{4.0-4.5}{\sqrt{(0.04)/(80)+(0.03)/(50)}}\\\\\Rightarrow z=15.0755672289\approx15.08](https://img.qammunity.org/2020/formulas/mathematics/college/1avnbke6inb1j8mvijkn3avlr5eh8vinfb.png)
Hence, the value of the test statistic will be 15.08 .