Question

3.Cards marked with numbers 13,14,15,.....,60 are placed in a box and mixed throughly.One card is drawn at random from the box.Find the probability that number on the drawn card is

(i)divisible by 5,(ii)a number which is a perfect square. (Ans. (i)5/24 (ii)1/12.)

Answer 1

Total no. of outcomes =
Using AP.,
a=12 d=1 an= 60
an = a + (n-1)d
60 =13 + (n-1)1
60= 13 + n - 1
60 - 12 =n
48 = n

(a) Favourable outcomes = 15, 20, 25, 30, 35, 40, 45, 50, 55 and 60
= 10
Therefore, P(E) = 10C1/48C1 = 10/48 = 5/24

(b) Is a perfect square = 16,25, 36 and 49 =4
Therefore P(E) = 4C1/48C1 = 4/48 = 1/12