A lumber company is making boards that are 2599.0 millimeters tall. If the boards are too long they must be trimmed, and if the boards are too short they cannot be used. A sample of 23 is made, and it is found that they have a mean of 2600.3 millimeters with a standard deviation of 13.0. A level of significance of 0.05 will be used to determine if the boards are either too long or too short. Assume the population distribution is approximately normal. Is there sufficient evidence to support the claim that the boards are either too long or too short?

Respuesta :

Answer:

There is no sufficient evidence to support  the claim that the boards are either too long or too short

Step-by-step explanation:

From the question we are told that

   The  population mean is [tex]\mu = 2599.0[/tex]

    The sample size is  [tex]n = 23[/tex]

     The  sample mean is  [tex]\= x = 2600.3 \ mm[/tex]

    The  standard deviation is  [tex]\sigma = 13.0[/tex]

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

     

The  null hypothesis  is  [tex]H_o : \mu = 2599.0[/tex]

  The  alternative  hypothesis is [tex]H_a : \mu \ne 2599.0[/tex]

Generally the test statistics is mathematically represented as

            [tex]t = \frac{ \= x - \mu }{ \frac{\sigma}{ \sqrt{n} } }[/tex]

=>          [tex]t = \frac{ 2600.3 - 2599.0 }{ \frac{13}{ \sqrt{ 23} } }[/tex]

=>            [tex]t = 0.3689[/tex]

Now from the normal distribution table  the critical value  of  [tex]\alpha[/tex] is  

    [tex]Z_{\alpha } = 1.645[/tex]

Hence from the evaluated and obtained value we see that

    [tex]t < Z_{\alpha }[/tex]

Hence we fail to reject the null hypothesis  

  Thus we can conclude that there is no sufficient evidence to support  the claim that the boards are either too long or too short