An engineer measured the Brinnel hardness of 25 pieces of ductile iron. The average hardness was...

An engineer measured the Brinnel hardness of 25 pieces of ductile iron. The average hardness was 172.52. The population standard deviation of Brinnel Hardness of ductile iron is 10.31. The engineer hypothesized the the mean Brinnel hardness of such ductile pieces is greater than 170. Test this hypothesis for a = 0.05.

Solutions

Expert Solution

Solution :

= 170

=172.52

=10.31

n = 25

This is the right tailed test .

The null and alternative hypothesis is ,

H0 : = 170

Ha : > 170

Test statistic = z

= ( - ) / / n

= (172.52-170) / 10.31 / 20

= 0.05

Test statistic = z = 0.05

P(z > 0.05 ) = 1 - P(z < 0.05 ) = 1 - 0.5199

P-value =0.4801

= 0.05

P-value >

0.4801 > 0.05

Fail to reject the null hypothesis .

There is not sufficient evidence to suggest that

orchestra answered 1 year ago

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