Judging on the basis of experience, a politician claims that 57%

of voters in a certain area have voted for an independent candidate in past elections. Suppose you surveyed 20

randomly selected people in that area, and 15

of them reported having voted for an independent candidate. The null hypothesis is that the overall proportion of voters in the area that have voted for an independent candidate is 57%.

What value of the test statistic should you report?

The test statistic is z= .