In Big C retail outlet, the last week record showed that out of 1000 mobile phones sold in which 85 were Vivo brand whereas the same branded mobile phones were as 120 out of 500 mobile phones sold in the current week. It is interested to test whether the current proportion of sales is more than that of previous week.

a) Set null and alternate hypotheses

b) Carry out the test using 1% level of significance.