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प्रश्न
The probability of a certain event is
विकल्प
0
1
greater than 1
less than 0
उत्तर
We have to find the probability of a certain event.
Note that the number of occurrence of an impossible event is same as the total number of trials. When we repeat the experiment, every times it occurs. This is the reason that’s why it is called certain event.
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`
Note that n is a positive integer, it can’t be zero. So, the probability of an impossible event is ` n/n=1`.
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संबंधित प्रश्न
A company selected 2400 families at random and survey them to determine a relationship between income level and the number of vehicles in a home. The information gathered is listed in the table below:
| Monthly income: (in Rs) |
Vehicles per family | |||
| 0 | 1 | 2 | Above 2 | |
| Less than 7000 7000-10000 10000-13000 13000-16000 16000 or more |
10 0 1 2 1 |
160 305 535 469 579 |
25 27 29 29 82 |
0 2 1 25 88 |
If a family is chosen, find the probability that family is:
(i) earning Rs10000-13000 per month and owning exactly 2 vehicles.
(ii) earning Rs 16000 or more per month and owning exactly 1 vehicle.
(iii) earning less than Rs 7000 per month and does not own any vehicle.
(iv) earning Rs 13000-16000 per month and owning more than 2 vehicle.
(v) owning not more than 1 vehicle
(vi) owning at least one vehicle.
Define an elementary event.
Three coins are tossed simultaneously 200 times with the following frequencies of different outcomes:
| Outcome | 3 heads | 2 heads | 1 head | No head |
| Frequency | 23 | 72 | 77 | 28 |
Find the probability of getting at most two heads.
Which of the following cannot be the probability of an event?
A coin is tossed 1000 times, if the probability of getting a tail is 3/8, how many times head is obtained?
The percentage of attendance of different classes in a year in a school is given below:
| Class: | X | IX | VIII | VII | VI | V |
| Attendance: | 30 | 62 | 85 | 92 | 76 | 55 |
What is the probability that the class attendance is more than 75%?
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 |
The probability that bulbs selected randomly from the lot has life less than 900 hours is:
A company selected 4000 households at random and surveyed them to find out a relationship between income level and the number of television sets in a home. The information so obtained is listed in the following table:
| Monthly income (in Rs) |
Number of Television/household | |||
| 0 | 1 | 2 | Above 2 | |
| < 10000 | 20 | 80 | 10 | 0 |
| 10000 – 14999 | 10 | 240 | 60 | 0 |
| 15000 – 19999 | 0 | 380 | 120 | 30 |
| 20000 – 24999 | 0 | 520 | 370 | 80 |
| 25000 and above | 0 | 1100 | 760 | 220 |
Find the probability of a household not having any television.
Two dice are thrown simultaneously 500 times. Each time the sum of two numbers appearing on their tops is noted and recorded as given in the following table:
| Sum | Frequency |
| 2 | 14 |
| 3 | 30 |
| 4 | 42 |
| 5 | 55 |
| 6 | 72 |
| 7 | 75 |
| 8 | 70 |
| 9 | 53 |
| 10 | 46 |
| 11 | 28 |
| 12 | 15 |
If the dice are thrown once more, what is the probability of getting a sum
- 3?
- more than 10?
- less than or equal to 5?
- between 8 and 12?
Two dice are thrown simultaneously 500 times. Each time the sum of two numbers appearing on their tops is noted and recorded as given in the following table:
| Sum | Frequency |
| 2 | 14 |
| 3 | 30 |
| 4 | 42 |
| 5 | 55 |
| 6 | 72 |
| 7 | 75 |
| 8 | 70 |
| 9 | 53 |
| 10 | 46 |
| 11 | 28 |
| 12 | 15 |
If the dice are thrown once more, what is the probability of getting a sum between 8 and 12?
