Advertisements
Advertisements
प्रश्न
The percentage of marks obtained by a student in monthly unit tests are given below:
| Unit test: | I | II | III | IV | V |
| Percentage of marks obtained: | 69 | 71 | 73 | 68 | 76 |
Find the probability that the student gets:
(i) more than 70% marks
(ii) less than 70% marks
(iii) a distinction
उत्तर
The total number of trials is 5.
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 getting more than 70% marks.
The number of times A happens is 3.
Therefore, we have
P (A) = `3/5`
=0.6
(ii) Let B be the event of getting less than 70% marks.
The number of times B happens is 2.
Therefore, we have
P (B) = `2/5`
=0.4
(iii) Let C be the event of getting a distinction.
The number of times C happens is 1.
Therefore, we have
P (C) = `1/5`
= 0.2
APPEARS IN
संबंधित प्रश्न
| Concentration of SO2 (in ppm) | Number of days (Frequency) |
| 0.00 − 0.04 | 4 |
| 0.04 − 0.08 | 9 |
| 0.08 − 0.12 | 9 |
| 0.12 − 0.16 | 2 |
| 0.16 − 0.20 | 4 |
| 0.20 − 0.24 | 2 |
| Total | 30 |
The above frequency distribution table represents the concentration of sulphur dioxide in the air in parts per million of a certain city for 30 days. Using this table, find the probability of the concentration of sulphur dioxide in the interval 0.12 − 0.16 on any of these days.
Three coins are tossed simultaneously 100 times with the following frequencies of different outcomes:
| Outcome: | No head | One head | Two heads | Three heads |
| Frequency: | 14 | 38 | 36 | 12 |
If the three coins are simultaneously tossed again, compute the probability of:
(i) 2 heads coming up.
(ii) 3 heads coming up.
(iii) at least one head coming up.
(iv) getting more heads than tails.
(v) getting more tails than heads.
Eleven bags of wheat flour, each marked 5 Kg, actually contained the following weights of flour (in kg):
4.97, 5.05, 5.08, 5.03, 5.00, 5.06, 5.08, 4.98, 5.04, 5.07, 5.00
Find the probability that any of these bags chosen at random contains more than 5 kg of flour.
Following table shows the birth month of 40 students of class IX.
| Jan | Feb | March | April | May | June | July | Aug | Sept | Oct | Nov | Dec |
| 3 | 4 | 2 | 2 | 5 | 1 | 2 | 5 | 3 | 4 | 4 | 4 |
Given below is the frequency distribution of wages (in Rs) of 30 workers in a certain factory:
| Wages (in Rs) | 110-130 | 130-150 | 150-170 | 170-190 | 190-210 | 210-230 | 230-250 |
| No. of workers | 3 | 4 | 5 | 6 | 5 | 4 | 3 |
A worker is selected at random. Find the probability that his wages are:
(i) less than Rs 150
(ii) at least Rs 210
(iii) more than or equal to 150 but less than Rs 210.
In a survey of 364 children aged 19 – 36 months, it was found that 91 liked to eat potato chips. If a child is selected at random, the probability that he/she does not like to eat potato chips is ______.
Two coins are tossed 1000 times and the outcomes are recorded as below:
| Number of heads | 2 | 1 | 0 |
| Frequency | 200 | 550 | 250 |
Based on this information, the probability for at most one head 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
Bulbs are packed in cartons each containing 40 bulbs. Seven hundred cartons were examined for defective bulbs and the results are given in the following table:
| Number of defective bulbs | 0 | 1 | 2 | 3 | 4 | 5 | 6 | more than 6 |
| Frequency | 400 | 180 | 48 | 41 | 18 | 8 | 3 | 2 |
One carton was selected at random. What is the probability that it has defective bulbs from 2 to 6?
Over the past 200 working days, the number of defective parts produced by a machine is given in the following table:
| Number of defective parts |
0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 |
| Days | 50 | 32 | 22 | 18 | 12 | 12 | 10 | 10 | 10 | 8 | 6 | 6 | 2 | 2 |
Determine the probability that tomorrow’s output will have
- no defective part
- atleast one defective part
- not more than 5 defective parts
- more than 13 defective parts
