Advertisements
Advertisements
प्रश्न
1500 families with 2 children were selected randomly and the following data were recorded:
| Number of girls in a family | 0 | 1 | 2 |
| Number of families | 211 | 814 | 475 |
(i) No girl
(ii) 1 girl
(iii) 2 girls
(iv) at most one girl
(v) more girls than boys
उत्तर
The total number of trials is 1500.
Remember the empirical or experimental or observed frequency approach to probability.
If n be the total number of trials of an experiment and A is an event associated to it such that A happens in m-trials. Then the empirical probability of happening of event A is denoted by p(A) and is given by
P(A) = `m/n`
(i) Let A be the event of having no girl.
The number of times A happens is 211.
Therefore, we have
P(A) = `211/1500`
=0.1406
(ii) Let B be the event of having one girl.
The number of times B happens is 814.
Therefore, we have
P(B) = `814/1500`
=0.5426
(iii) Let C be the event of having two girls.
The number of times C happens is 475.
Therefore, we have
P(C) = `475/1500`
=0.3166
(iv) Let D be the event of having at most one girl.
The number of times D happens is 211+814=1025.
Therefore, we have
P(D) = `1025/1500`
=0.6833
(v) Let E be the event of having more girls than boys.
The number of times E happens is 475.
Therefore, we have
P(E) = `475/1500`
=0.3166
APPEARS IN
संबंधित प्रश्न
The distance (in km) of 40 engineers from their residence to their place of work were found as follows.
| 5 | 3 | 10 | 20 | 25 | 11 | 13 | 7 | 12 | 31 |
| 19 | 10 | 12 | 17 | 18 | 11 | 32 | 17 | 16 | 2 |
| 7 | 9 | 7 | 8 | 3 | 5 | 12 | 15 | 18 | 3 |
| 12 | 14 | 2 | 9 | 6 | 15 | 15 | 7 | 6 | 12 |
What is the empirical probability that an engineer lives:-
(i) less than 7 km from her place of work?What is the empirical probability that an engineer lives:
(ii) more than or equal to 7 km from her place of work?
(iii) within 1/2 km from her place of work?
The following table gives the life time of 400 neon lamps:
| Life time (in hours) |
300-400 | 400-500 | 500-600 | 600-700 | 700-800 | 800-900 | 900-1000 |
| Number of lamps: | 14 | 56 | 60 | 86 | 74 | 62 | 48 |
A bulb is selected of random, Find the probability that the the life time of the selected bulb is:
(i) less than 400
(ii) between 300 to 800 hours
(iii) at least 700 hours.
Define an event.
A big contains 4 white balls and some red balls. If the probability of drawing a white ball from the bag is `2/5`, find the number of red balls in the bag.
what is the probability of getting at least two heads?
Which of the following cannot be the probability of an event?
In a sample study of 642 people, it was found that 514 people have a high school certificate. If a person is selected at random, the probability that the person has a high school certificate is ______.
In a medical examination of students of a class, the following blood groups are recorded:
| Blood group | A | AB | B | O |
| Number of students | 10 | 13 | 12 | 5 |
A student is selected at random from the class. The probability that he/she has blood group B, is:
80 bulbs are selected at random from a lot and their life time (in hrs) is recorded in the form of a frequency table given below:
| Life time (in hours) | 300 | 500 | 700 | 900 | 1100 |
| Frequency | 10 | 12 | 23 | 25 | 10 |
One bulb is selected at random from the lot. The probability that its life is 1150 hours, is
A recent survey found that the ages of workers in a factory is distributed as follows:
| Age (in years) | 20 – 29 | 30 – 39 | 40 – 49 | 50 – 59 | 60 and above |
| Number of workers | 38 | 27 | 86 | 46 | 3 |
If a person is selected at random, find the probability that the person is:
- 40 years or more
- under 40 years
- having age from 30 to 39 years
- under 60 but over 39 years
