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Friday, 28 December 2018
Sunday, 23 December 2018
REVISION ASSIGNMENT 02_24.12.2018
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Class
IX Revision assignment 02 Date:-
24.12.2018
Chapters:- Probability and Statistics
1.
A bag containing 12 marbles. There are 3 red
marbles, 4 blue marbles and 5 green marbles, find the probability that he will
draw a blue marble.
2.
The percentage of marks obtained by a student in
monthly unit tests is given below:
Unit Test
|
i
|
ii
|
iii
|
iv
|
v
|
Percentage
|
69
|
71
|
73
|
68
|
76
|
Find
the probability that the student gets more than 68% marks.
3.
1000 families with 2 children were selected
randomly and the following data was recorded:
No. of girls in a family
|
0
|
1
|
2
|
No. of families
|
200
|
500
|
300
|
If a family
is chosen at random, compute the probability that it has
(a)
no girl, (b) at least one girl
4.
In a match, a batsman hits a boundary 5 times
out of 20 balls he plays. Find the probability that he did not hit a boundary.
5.
The record of a weather station shows that out of
the past 400 consecutive days, its weather forecasts were correct 175 times.
(i) What is the probability that on a
given day it was correct?
(ii) What is the probability that it was
not correct on a given day?
6.
Two coins are tossed simultaneously 100 times
and we get the following outcomes :
(i)
No head = 30 (ii) One head = 20.
Find
the probability of getting two heads.
7.
A teacher wanted to analyze the performance of
two sections of students in a mathematics test of 100 marks. Looking at their
performances, she found that a few students got under 20 marks and a few got 70
marks or above. So she decided to group them into intervals of varying sizes as
follows: 0 − 20, 20 − 30… 60 − 70, 70 − 100. Then she formed the following
table:
Marks
|
No. of Students
|
0-20
|
7
|
20-30
|
10
|
30-40
|
10
|
40-50
|
20
|
50-60
|
20
|
60-70
|
15
|
70 and above
|
8
|
Total
|
90
|
(i)
Find the probability that a student obtained
less than 20 % in the mathematics test.
(ii)
(ii) Find the probability that a student
obtained marks 60 or above
8.
Write the class size in each of the following:
(a) 0 – 4, 5 – 9, 10 – 14 (b) 10 – 19, 20 – 29, 30 – 39
9.
Write class size and class limits in each of the
following if the class marks are: (a) 104, 114, 124, 134, 144, and 154 (b) 47,
52, 57, 62, 67, 72, 77 (c) 12.5, 17.5, 22.5, 27.5, 32.5, and 37.5
10.
The monthly wages of 30 workers in a factory are
given below:- 830, 835, 890, 810, 835, 836, 869, 894, 898, 890, 820, 860, 832,
833, 855, 845, 804, 808, 812, 840, 885, 835, 836, 878, 840, 868, 890, 806, 840,
890
(a)
Form frequency distribution table with class
size 10
(b)
Find
cumulative frequency
(c)
Draw
histogram and frequency polygon 4.
11.
Draw histogram of the following distribution:
Marks
|
No. of students
|
0-10
|
5
|
10-20
|
10
|
20-30
|
4
|
30-40
|
6
|
40-50
|
7
|
50-60
|
3
|
60-70
|
2
|
12.
The following are the scores of two groups of
class IX students in a test.
Scores
|
Group A
|
Group B
|
32-34
|
4
|
2
|
35-37
|
10
|
3
|
38-40
|
15
|
4
|
41-43
|
18
|
8
|
44-46
|
20
|
12
|
47-49
|
12
|
17
|
50-52
|
13
|
22
|
Compare the scores of two groups by using frequency polygon.
13.
The mean of 40 observations was 160. It was
detected on rechecking that the value of 165 was wrongly copied as 125 for
computation of mean. Find the correct mean.
14.
The mean monthly salary of 10 members of a group
is Rs 1445, one more member whose monthly salary is Rs
1500 has joined the group. Find the mean
monthly salary of 11 members.
15.
If the mean of the following distribution is 6,
find the value of P.
X
|
2
|
4
|
6
|
8
|
P+5
|
F
|
3
|
2
|
3
|
1
|
2
|
*Date of submission –
26.12.2018 and test of revision assignment 1 & 2 on 27.12.2018
Thursday, 20 December 2018
REVISION ASSIGNMENT 01
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