An investigator predicts that dog owners in the country spend more time walking their dogs than do dog owners in the city. The investigator gets a sample of 21 country owners and 23 city owners. The mean number of hours per week that city owners spend walking their dogs is 10.0. The standard deviation of hours spent walking the dog by city owners is 3.0. The mean number of hours country owners spent walking theirs dogs per week was 15.0. The standard deviation of the number of hours spent walking the dog by owners in the country was 4.0. Do dog owners in the country spend more time walking their dogs than do dog owners in the city?

Respuesta :

Answer:

Yes  dog owners in the country spend more time walking their dogs than do dog owners in the city

Step-by-step explanation:

From the question we are told that

    The sample size from country is [tex]n_1 = 21[/tex]

     The  sample  size from city is  [tex]n_2 = 23[/tex]

     The  sample  mean for  country is   [tex]\= x_1 =  15 [/tex]

      The  Sample  mean for  city is  [tex]\= x_2 =  10[/tex]

       The  standard deviation for country  is [tex]\sigma _1 =  4[/tex]

        The standard deviation for  city is  [tex]\sigma _2 =  3[/tex]

Let the level of significance is  [tex]\alpha = 0.05[/tex]

The null hypothesis is  [tex]H_o : \mu_1 = \mu_2[/tex]

The  alternative hypothesis is  [tex]H_a : \mu_1 > \mu_2[/tex]

 The  pooled standard deviation is  mathematically represented as

       [tex]s =  \sqrt{ \frac{s_1 ^2  *  (n_1 - 1 ) + s_2 ^2 *  (n_2 - 1 )}{ df} }[/tex]

Here  df is the degree of freedom which is mathematically represented as

          [tex]df =  n_1 + n_2  - 2[/tex]

         [tex]df =  21 + 23 -2 [/tex]

        [tex]df =  42[/tex]

So

    [tex]s =  \sqrt{ \frac{4 ^2  *  (15.0 - 1 ) + 3 ^2 *  (10 - 1 )}{ 42} }[/tex]  

    [tex]s =  3.5[/tex]

Generally the test statistics is mathematically represented

        [tex]t =  \frac{\= x_1 - \= x_2 }{ s *  \sqrt{\frac{1}{n_1} +\frac{1}{n_2}  } }[/tex]

          [tex]t =  \frac{ 15 -10 }{ 3.5 * \sqrt{\frac{1}{ 21 } + \frac{1}{23} } }[/tex]

[tex]t =  4.733[/tex]

Generally the p-value  is obtained from the student t-distribution table   table , the value  is  

         [tex]P(T >   4.733)=  t_{4.733,  42 } = 0.000013  [/tex]

From the calculation we see that

         [tex]p-value  < \alpha[/tex]

So we reject the null hypothesis

Hence we can conclude that there is  sufficient evidence to support the claim that dog owners in the country spend more time walking their dogs than do dog owners in the city