Question

Problem 1.) A researcher claims that 96% of college graduates say their college degree has
been a good investment. In a random sample of 2000 graduates, 1500 say their college degree has
been a good investment. At a = 0.05 is there enough evidence to reject the researcher's claim?

Answer 1

Answer:

 |Z| = |-52.5|  = 52.5 > 1.96 at 0.05 level of significance

 Null  hypothesis is rejected

We rejected the researcher's claim

A researcher do not claims that 96% of college graduates say their college degree has been  a good investment.

Step-by-step explanation:

Explanation:-

Given data A researcher claims that 96% of college graduates say their college degree has  been a good investment.

Population proportion 'P' = 0.96

                                       Q = 1-P = 1- 0.96 = 0.04

In a random sample of 2000 graduates, 1500 say their college degree has

been a good investment.

Sample proportion

                       $p^{-} = \frac{x}{n} = \frac{1500}{2000} = 0.75$

Level of significance  ∝ = 0.05

$Z_{\frac{\alpha }{2} } = Z_{\frac{0.05}{2} } = Z_{0.025} = 1.96$

Test statistic

                        $Z = \frac{p^{-} - P }{\sqrt{\frac{PQ}{n} } }$

                        $Z = \frac{0.75 - 0.96 }{\sqrt{\frac{0.96 X 0.04}{2000} } }$

                        $Z = \frac{-0.21}{0.00435} = -52.5$

    |Z| = |-52.5|  = 52.5 > 1.96 at 0.05 level of significance

  Null  hypothesis is rejected

  We rejected the researcher's claim

Conclusion:-

A researcher do not claims that 96% of college graduates say their college degree has been  a good investment.