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Sagot :
Answer:
a) -0.94
b) 0.3472
c) -2.327, 2.327
Step-by-step explanation:
A claim is made that the proportion of 6-10 year-old children who play sports is not equal to 0.5.
At the null hypothesis, we test if the proportion is of 0.5, that is:
[tex]H_0: p = 0.5[/tex]
At the alternative hypothesis, we test if the proportion is different from 0.5, that is:
[tex]H_1: p \neq 0.5[/tex]
The test statistic is:
[tex]z = \frac{X - \mu}{\frac{\sigma}{\sqrt{n}}}[/tex]
In which X is the sample mean, [tex]\mu[/tex] is the value tested at the null hypothesis, [tex]\sigma[/tex] is the standard deviation and n is the size of the sample.
0.5 is tested at the null hypothesis:
This means that [tex]\mu = 0.5, \sigma = \sqrt{0.5*(1-0.5)} = 0.5[/tex]
A random sample of 551 children aged 6-10 showed that 48% of them play a sport.
This means that [tex]n = 551, X = 0.48[/tex]
(a) Calculate the value of the test statistic used in this test.
[tex]z = \frac{X - \mu}{\frac{\sigma}{\sqrt{n}}}[/tex]
[tex]z = \frac{0.48 - 0.5}{\frac{0.5}{\sqrt{551}}}[/tex]
[tex]z = -0.94[/tex]
So the answer is -0.94.
(b) Use your calculator to find the P-value of this test.
The p-value of the test is the probability that the sample proportion differs from 0.5 by at least 0.02, which is P(|z| > 0.94), which is 2 multiplied by the p-value of Z = -0.94.
Looking at the z-table, z = -0.94 has a p-value of 0.1736.
2*0.1736 = 0.3472, so 0.3472 is the answer to option b.
(c) Use your calculator to find the critical value(s) used to test this claim at the 0.02 significance level.
Two-tailed test(test if the mean differs from a value), Z with a p-value of 0.02/2 = 0.01 or 1 - 0.01 = 0.99.
Looking at the z-table, this is z = -2.327 or z = 2.327.
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