You will be doing a test goodness of fit test. The null hypothesis is that there is no difference in preference, and so as the total number of observations is 535, the expected frequencies for each brand are all 107.

So We have a table:

Then:Code:O(bserved) E(xpected) 118 107 92 107 135 107 88 107 102 107

and we have 4 degrees of freedom.

You will need to look up the p-value for the value of in a table to complete the test.

CB