Home
Class 10
MATHS
A box contains 90 discs which are number...

A box contains 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 square number (iii) a number divisible by 5.

Text Solution

Verified by Experts

We have, n(S)=90
(i) Let A be the event of getting "a two-digit number".
`therefore` Favourable cases are 10, 11, 12, 13, 14,…, 90.
`therefore" "n(A)=81`
`therefore "P(A)=(n(A))/(n(S))=(81)/(90)=(9)/(10)`
(ii) Let B be the event of getting "a number divisible by 5".
`therefore` Favourable cases are 10, 15, 20, 25, 30, ..., 90.
Let these are n in numbers.
`therefore" "T_(n)=90`
`therefore" "10+(n-1)15=90" "[a_(n) of A.P. = a+ (n-1)d]`
`rArr" "(n-1)5=80 rArr n-1=16 rArr n=17`
`therefore" "n(B)=17`
`therefore" "P(B)=(n(B))/(n(S))=(17)/(90)`
Promotional Banner

Topper's Solved these Questions

  • PROBABILITY

    NAGEEN PRAKASHAN ENGLISH|Exercise Problems From NCERT /exemplar|10 Videos

  • PROBABILITY

    NAGEEN PRAKASHAN ENGLISH|Exercise Exercise|29 Videos

  • POLYNOMIALS

    NAGEEN PRAKASHAN ENGLISH|Exercise Revision Exercise Long Answer Questions|4 Videos

  • QUADRATIC EQUATIONS

    NAGEEN PRAKASHAN ENGLISH|Exercise Revision Exercise Long Answer Questions|6 Videos

Similar Questions

Explore conceptually related problems

A box contains 90 discs, numbered from 1 to 90. If one disc is drawn at random from the box,find the probability that it bears a prime number < 23.

A bag contains cards which are numbered from 2 to 90. A card is drawn at random from the bag. Find the probability that it bears (i) a two digit number (ii) a number which is a perfect square

A bag contains 100 identical marble stones which are numbered from 1 to 100. If one stone is drawn at random from the bag, find the probability that it bears a perfect square number.

A bag contains 100 identical marble stones which are numbered form 1 to 100. If one stone is a drawn at random from the bag, find the probability that it bears (i) a number divisible by 4 or 5 ,(ii) a number divisible by 4 and 5.

A bag contains 100 identical marble stones which are numbered from 1 to 100. If one stone is drawn at random from the bag, find the probability that it bears a number divisible by 4.

A bag contains 100 identical marble stones which are numbered from 1 to 100. If one stone is drawn at random from the bag, find the probability that it bears : (iii) a number divisible by 5.

A bag contains 100 identical marble stones which are numbered from 1 to 100. If one stone is drawn at random from the bag, find the probability that it bears : (iv) a number divisible by 4 or 5.

A bag contains 100 identical marble stones which are numbered from 1 to 100. If one stone is drawn at random from the bag, find the probability that it bears : (v) a number divisible by 4 and 5.

Cards numbered from 11 to 60 are kept in a box. If a card is drawn at random from the box, find the probability that the number on the drawn cards is (i) an odd number (ii) a perfect square number

A box contains 90 discs, numbered from 1 to 90. If one disc is drawn at random from the box, the probability that it bears a prime number less than 23, is 7/(90) (b) (10)/(90) (c) 4/(45) (d) 9/(89)