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Question A box contains 20 balls bearing numbers 1,2,3,...,20 respectively. A ball is drawn at random from the box what is the probability that the number on the ball is
(i) An odd number
(ii) Divisible by 2 or 3
(iii) A prime number
(iv) Not divisible by 10 ​

Sagot :

Solution

Correct option is B)

______________________________________

Since, total balls = 20

(i) odd numbers from 1 to 20 are:

1,3,5,7,9,11,13,15,17,19

no. of balls bearing odd numbers = 10

  • favorable outcomes= 10
  • [tex]probability = \frac{10}{20} = \frac{1}{2} [/tex]

_____________________________________

(ii) number divisible by 2 or 3 from 1 to 20 are:

    2,3,4,6,8,9,10,12,14,15,16,18,20

    no. of balls bearing number divisible by 2 or 3 = 13

  • favorable outcomes= 13
  • [tex]probability \frac{13}{20} [/tex]

____________________________________

(iii) prime numbers from 1 to 20 are:

  2,3,5,7,,11,13,17,19

   no. of balls bearing prime number = 8

  • favorable outcomes= 8
  • [tex]probability =  \frac{8}{20} = \frac{2}{5}
  • [/tex]

___________________________________

(iv) No. of balls bearing number not divisible by 10 = 18

  • favorable outcomes= 18
  • [tex]probability = \frac{18}{20} = \frac{9}{10} [/tex]

#CARRY ON LEARNING

– zhen ❦

Solution

Correct option is B)

______________________________________

Since, total balls = 20

(i) odd numbers from 1 to 20 are:

1,3,5,7,9,11,13,15,17,19

no. of balls bearing odd numbers = 10

  • favorable outcomes= 10
  • [tex]probability = \frac{10}{20} = \frac{1}{2} [/tex]

_____________________________________

(ii) number divisible by 2 or 3 from 1 to 20 are:

    2,3,4,6,8,9,10,12,14,15,16,18,20

    no. of balls bearing number divisible by 2 or 3 = 13

  • favorable outcomes= 13
  • [tex]probability \frac{13}{20} [/tex]

____________________________________

(iii) prime numbers from 1 to 20 are:

  2,3,5,7,,11,13,17,19

   no. of balls bearing prime number = 8

  • favorable outcomes= 8
  • [tex]probability =  \frac{8}{20} = \frac{2}{5}
  • [/tex]

___________________________________

(iv) No. of balls bearing number not divisible by 10 = 18

  • favorable outcomes= 18
  • [tex]probability = \frac{18}{20} = \frac{9}{10} [/tex]

#CARRY ON LEARNING

– YUSHIRO