Records of 40 used passanger cars and 40 used pickup tricks were randomly selected to investigate whether there was any difference in the mean time in years that they were kept by original owner before being sold. for cars, the mean was 5.3 years with standard deviation 2.2 years. for pickup trucks, the mean was 7.1 years with standard deviation 3.0 years. test the hypothesis that there is a difference in the means against the null hypothesis that there is no difference. use the 1% level of significance.

There is significant difference between the two average times

Step-by-step explanation:

This test would be comparison of two means where only sample variances and means are given.

Since variances are unequal we have to do t test for unequal variances.

(Two tailed test)(x represents grou I cars, and Y group 2 trucks)

Group   Group One     Group Two  

Mean5.3007.100

SD2.2003.000

SEM0.3480.474

N40      40  

The mean of Group One minus Group Two equals -1.800

standard error of difference = 0.588

t = 3.0601

 df = 78

The two-tailed P value equals 0.0030

Since p <1% we reject null hypothesis

There is significant difference between the two average times

the highest percentage for deaths in construction from highest to lowest is as follows: falls, struck by objects, electrocution, and caught-in/between. these four are collectively known as fatal four.

in the case of falls, the type that is responsible for the overall highest death in the category is falls from roofs.