Question

You no longer believe that the population standard deviation in the yearly sales of the Nikon D5 camera for this population of stores is a known quantity. You therefore will use the standard deviation of a representative sample of stores as an estimate of the unknown population standard deviation in the yearly sales of the camera. You collect data from a random sample of stores once again. This data is shown in appendix one below. Once again at each of the 10% and 5% levels of significance, are yearly mean sales greater than 150 units for this population of stores? Again, in your memo, comment upon the effect of the change in the level of significance on your decision, if necessary. Also, compare, at each level of significance, the results of this portion of the problem to those of the previous part. Account for any difference in your decisions at each level of significance between the two parts of the problem.

            Appendix One: (Sales in units)

            134 187 212 215 155 150 187 176 122 189 231

145 167 187 230 165 176 187 190 199 210 210

178 190 197 139 148 137 200 189 180 201 195

187 190

Answer 1

For the given data

mean = 181.57

S.d = 26.9534

n = 35

At alpha = 0.10

Test Statistics

observed that t = 6.929 , df = 34 , ( right tailed )

we get p value = 0

At alpha = 0.05 l.o.s

Using the P-value approach: The p-value is p=0, and since p=0<0.05, it is concluded that the null hypothesis is rejected.

At alpha = 0.10  l.o.s

Using the P-value approach: The p-value isp=0, and since p=0<0.10 , it is concluded that the null hypothesis is rejected.

Conclusion

It is concluded that the null hypothesis Ho is rejected. Therefore, there is enough evidence to claim that the

early mean sales greater than 150 units for this population of stores   at each of the 10% and 5% levels of significance,