(Solved): Many freeways have service (or logo) signs that give information on attractio ...

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Many freeways have service (or logo) signs that give information on attractions, camping, lodging, food and gas services prior to off-ramps. These sign typically do not provide information on distances. A study reported that in one investigation, six sites along interstate highways where service signs are posted were selected. For each site, crash data was obtained for a three year period before distance information was added to the service signs and for a one year period afterward. The number of crashes per week before and after the sign changes were as follows: a) Is there evidence that there was a change in the mean number of crashes before and after the addition of distance information on the signs? b) Find a \( 95 \% \) confidence interval for the true mean difference between before and after the addition of the distance information on the signs.