When garbage is thrown into recycle bins, the contamination makes recycle handling very expensive. The government of a large city launched an extensive education campaign to reduce contamination. To access the success of the campaign, a researcher compared the data for each of 21 collection routes before and after, with the results given below. Is this sufficient evidence at the 5% significance level to conclude that there was a reduction after the campaign? Do not round intermediate calculations.(10 marks)

Before

After

n

21

21

Mean contamination per person (kg)

24.9

15.20

Sample standard deviation

1.21

3.64