a) Mean - add numbers of animals, and then divide by the number of students.
numbers of animals =1*20+2*11+3*18+4*10+5*3 +6*18 = 259
number of students = 20+20+11+18+10+3+18 = 100
mean=numbers of animals /number of students = 259 / 100=2.59
b) median
You can write 20 zeroes, 20 ones, 11 twos and so on. and the remove from left and right equal amount of number, when you get in the middle,it is going to be median
20 "0", 20 "1", 11 "2", 18 "3", 10 "4", 5 "3", 18 "6"
51 place 51 place
From the left 20+20+11=51 places
18+5+10+18=51 places
We can see that no single middle number. In the middle is going to be two numbers 2 and 3, and divide them by 2.
(2+3)/2=2.5 median
3) (127/151)*100%≈ 84.11%
