NCERT Class 11-Math՚s: Exemplar Chapter – 16 Probability Part 4 (For CBSE, ICSE, IAS, NET, NRA 2023)
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Question 6:
Probability that a truck stopped at a roadblock will have faulty brakes or badly worn tires are and , respectively. Also, the probability is that a truck stopped at the roadblock will have faulty brakes and/or badly working tires. What is the probability that a truck stopped at this roadblock will have faulty brakes as well as badly worn tires?
Answer:
Let B be the event that a truck stopped at the roadblock will have faulty brakes and T be the event that it will have badly worn tires. We have and
and
So
Question 7:
If a person visits his dentist, suppose the probability that he will have his teeth cleaned is , the probability that he will have a cavity filled is , the probability that he will have a tooth extracted is , the probability that he will have a teeth cleaned and a cavity filled is , the probability that he will have his teeth cleaned and a tooth extracted is , the probability that he will have a cavity filled and a tooth extracted is , and the probability that he will have his teeth cleaned, a cavity filled, and a tooth extracted is . What is the probability that a person visiting his dentist will have atleast one of these things done to him?
Answer:
Let C be the event that the person will have his teeth cleaned and F and E be the event of getting cavity filled or tooth extracted, respectively. We are given
,
Now,
Long Answer Type
Question 8:
An urn contains twenty white slips of paper numbered from 1 through 20, ten red slips of paper numbered from 1 through 10, forty yellow slips of paper numbered from 1 through 40, and ten blue slips of paper numbered from 1 through 10. If these 80 slips of paper are thoroughly shuffled so that each slip has the same probability of being drawn. Find the probabilities of drawing a slip of paper that is
(a) Blue or white
(b) Numbered or
(c) Red or yellow and numbered or
(d) Numbered , or ;
(e) White and numbered higher than or yellow and numbered higher than .
Answer:
(a)
(b)
(c)
(d)
(e) P (White and numbered higher than or Yellow and numbered higher than 26)