In the last presidential election, before the candidates started their major campaigns, the percentages of

registered voters who favored the various candidates were as follows.

Percentages

Republicans

34%

Democrats

43%

Independents

23%

After the major campaigns began, a random sample of 400 voters showed that 172 favored the Republican candidate; 164 were in favor of the Democratic candidate; and 64 favored the Independent candidate. We are interested in determining whether the proportion of voters who favored the various candidates had changed.

How do I calculate the expected frequencies??