Originally Posted by

**lpd** Hi I have this question.

If $\displaystyle 26$ of $\displaystyle 200$ tyres of $\displaystyle brand A$ failed to last $\displaystyle 20,000$ miles, while the corresponding gures for $\displaystyle 200$ tires of$\displaystyle Brands B$, $\displaystyle C$, and $\displaystyle D$ were $\displaystyle 23$, $\displaystyle 15$ and $\displaystyle 32$, **test the null hypothesis** that there is no dierence in the quality of the four kinds of tyres.

Use $\displaystyle \alpha = 0.05$.

Thank-you so much!