Question

a box contain 90 discs which are numbered from 1 to 90 . if one disc is drawn at random from the box ,find the probability that it bears ;
(i) a two digit number
(ii) a perfect squared number
(iii) a number divisible by 5​

Answer 1

Answer:

i) 9/10

ii) 1/10

iii) 1/5

Step-by-step explanation:

i) Out of 1 to 90, all numbers from 10 till 90 are 2 digit numbers. Hence there are 81 two-digit numbers in that range, so probability is 81/90 = 9/10.

ii) Out of 1 to 90, all numbers from 10 till 90 are 2 digit numbers. Hence there are 81 two-digit numbers in that range, so probability is 81/90 = 9/10.

iii) Out of 1 to 90, all numbers that are multiples of 5 are 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90 => total 18 numbers. A quick way to calculate this is 90/5 = 18. Hence probability is 18/90 = 1/5.

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Answer 2

Answer:

(i) $\frac{9}{10}$

(ii)$\frac{1}{10}$

(iii)$\frac{1}{5}$

Step-by-step explanation:

(i) P(E)= $\frac{No. of possible outcomes}{Total no. of outcomes}$

         = $\frac{81}{90}$

         = $\frac{9}{10}$

(ii) P(E)= $\frac{No. of possible outcomes}{Total no. of outcomes}$

          = $\frac{9}{90}$

          = $\frac{1}{10}$

(iii) P(E)= $\frac{No. of possible outcomes}{Total no. of outcomes}$

           = $\frac{18}{90}$

           = $\frac{1}{5}$