1. A number is chosen from 1 to 20. Find the probability that the number chosen is :
(i) a prime number (ii) a composite number
(iii) a square number (iv) an odd number
(v) an even number (vi) number between 7 and 14

Total no. of nos. = 20
P(E) = no . of favourable outcomes / total no. of outcomes
i) no. of prime nos. = 8 (i.e 2, 3, 5, 7, 11, 13, 17, 19)
P(E) = 8/20 = 2/5

ii) no. of composite nos. = 11 (i.e 4, 6, 8, 9,10, 12, 14, 15, 16, 18, 20)
P(E) = 11/20

iii) no. of square nos. = 4 (i.e 1, 4, 9, 16)
P(E) = 4/20 = 1/5

iv) no. of odd nos. = 10 (i.e 1, 3, 5, 7, 9, 11, 13, 15, 17, 19)
P(E) = 10/20 = 1/2

v) no. of even nos. = 20 - (no. of odd nos.) = 20-10 = 10
P(E) = 10/20 = 1/2

vi) no. of nos. between 7 and 14 = 6(i.e 8, 9, 10, 11, 12, 13)
P(E) = 6/20 = 3/10

 (i) a prime number   =    8 / 20    =  2 / 5

(ii) a composite number   =  11 / 20 
(iii) a square number    =     3 / 20

(iv) an odd number    =    10 / 20    =   1 / 2
(v) an even number    =    10 / 20    =   1 /     =  6 /20   =   3 / /202

(vi) number between 7 and 14