A publisher reports that 38 \% of their readers own a particular make of car. A marketing executive wants to test the claim that the percentage is actually above the reported percentage. A random sample of 350 found that $42\mathrm{\%}$ of the readers owned a particular make of car. Is there sufficient evidence at the 0.10 level to support the exccutive's claim?

Step 2 of 7: Find the value of the test statistic. Round your answer to two decimal places.
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Step 1 ：The problem is asking for the value of the test statistic in a hypothesis test for a proportion. The test statistic in this case is a z-score, which is calculated as $(p̂-p0)/\sqrt{(p0\ast (1-p0))/n}$, where $p̂$ is the sample proportion, $p0$ is the population proportion under the null hypothesis, and $n$ is the sample size. In this case, $p̂=0.42$, $p0=0.38$, and $n=350$.

Step 2 ：Substitute the given values into the formula: $z=(0.42-0.38)/\sqrt{(0.38\ast (1-0.38))/350}$

Step 3 ：Calculate the z-score to get the test statistic for the hypothesis test.

Step 4 ：The calculated z-score is 1.54.

Step 5 ：Final Answer: The value of the test statistic is $\boxed{{\displaystyle 1.54}}$.