# Answer in Statistics and Probability for Aven #241076

It is known from the records of the city schools that the standard deviation of mathematics test scores on the XYZ test is 5. A sample of 200 pupils from the system was taken and it was found out that the sample mean score is 75. Previous tests showed the population mean to be 70. Is it safe to conclude that the sample is significantly different from the population?

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Answer in Statistics and Probability for Aven #241076
Just from $13/Page The following null and alternative hypotheses need to be tested: “H_0: \mu=70” “H_1:\mu\not=70” This corresponds to a two-tailed test, for which a z-test for one mean, with known population standard deviation will be used. Based on the information provided, the significance level is “\alpha = 0.05,” and the critical value for a two-tailed test is “z_c = 1.96nn.” The rejection region for this two-tailed test is “R = \{z: |z| > 1.96\}.” The z-statistic is computed as follows: “z=\dfrac{\bar{x}-\mu}{\sigma/\sqrt{n}}=\dfrac{75-70}{5/\sqrt{200}}=10\sqrt{2}” “\approx14.142” Since it is observed that “|z| = 14.142 >1.96= z_c,” it is then concluded that the null hypothesis is rejected. Using the P-value approach: The p-value for two-tailed “\alpha=0.05,” “z=14.142” is “p=2P(z>14.142)\approx0,” and since “p = 0 < 0.05=\alpha,” it is concluded that the null hypothesis is rejected. Therefore, there is enough evidence to claim that the sample is significantly different from the population, at the “u03b1=0.05” significance level. # What Will You Get? We provide professional writing services to help you score straight A’s by submitting custom written assignments that mirror your guidelines. #### Premium Quality Get result-oriented writing and never worry about grades anymore. We follow the highest quality standards to make sure that you get perfect assignments. #### Experienced Writers Our writers have experience in dealing with papers of every educational level. You can surely rely on the expertise of our qualified professionals. #### On-Time Delivery Your deadline is our threshold for success and we take it very seriously. We make sure you receive your papers before your predefined time. #### 24/7 Customer Support Someone from our customer support team is always here to respond to your questions. So, hit us up if you have got any ambiguity or concern. #### Complete Confidentiality Sit back and relax while we help you out with writing your papers. We have an ultimate policy for keeping your personal and order-related details a secret. #### Authentic Sources We assure you that your document will be thoroughly checked for plagiarism and grammatical errors as we use highly authentic and licit sources. #### Moneyback Guarantee Still reluctant about placing an order? Our 100% Moneyback Guarantee backs you up on rare occasions where you aren’t satisfied with the writing. #### Order Tracking You don’t have to wait for an update for hours; you can track the progress of your order any time you want. We share the status after each step. #### Areas of Expertise Although you can leverage our expertise for any writing task, we have a knack for creating flawless papers for the following document types. # Trusted Partner of 9650+ Students for Writing From brainstorming your paper's outline to perfecting its grammar, we perform every step carefully to make your paper worthy of A grade. ##### Preferred Writer Hire your preferred writer anytime. Simply specify if you want your preferred expert to write your paper and we’ll make that happen. ##### Grammar Check Report Get an elaborate and authentic grammar check report with your work to have the grammar goodness sealed in your document. ##### One Page Summary You can purchase this feature if you want our writers to sum up your paper in the form of a concise and well-articulated summary. ##### Plagiarism Report You don’t have to worry about plagiarism anymore. Get a plagiarism report to certify the uniqueness of your work. ## Free Features$66FREE

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