Please solve the question quickly and clearly

note:

a=2

b=0

c=2

d=0

e=0

f=2

6. The mean time taken to submit an assignment by a student was 20 days according to the previous semester record. The Exam office claimed that this year the submission time increased due to the natural calamities. Was the submission time really increased or not. Test the hypothesis with a 5% level of significance. The time taken by 15 students to submit their assignment are given below (14+a), (15+b), (16+c),(17+d),(18+),19, (20+a), (21+b), (22+c), (23+d),(24+e),(25+f), (26+a), (27+b), (28+c). (Follow the "Instructions to students" to replace a,b,c,d,e & f by its values)