Q3 of 105 Page 582

Suppose that 5% of men and 0.25% of women have grey hair. A grey haired person is selected at random. What is the probability of this person being male?

Assume that there are equal number of males and females.

It is given in the question that,

5% of men and 0.25% of women have grey hair


∴ Total % of people having grey hair = 5 + 0.25


= 5.25 %


Hence, Probability of having a selected person male having grey hair,



More from this chapter

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1

A and B are two events such that P (A) ≠ 0. Find P(B|A), if:

(i) A is a subset of B


(ii) A ∩ B = φ

 2

A couple has two children,

(i) Find the probability that both children are males, if it is known that at least one of the children is male.


(ii) Find the probability that both children are females, if it is known that the elder child is a female.

 4

Suppose that 90% of people are right-handed. What is the probability that at most 6 of a random sample of 10 people are right-handed?

 5

An urn contains 25 balls of which 10 balls bear a mark 'X' and the remaining 15 bear a mark 'Y'. A ball is drawn at random from the urn, its mark is noted down and it is replaced. If 6 balls are drawn in this way, find the probability that:

(i) All will bear 'X' mark.


(ii) Not more than 2 will bear 'Y' mark.


(iii) At least one ball will bear 'Y' mark.


(iv) The number of balls with 'X' mark and 'Y' mark will be equal.