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YSA
Model Paper
Paper
Mathematics Class:
9th
Answer
Key
Section - B
Q.2
i.
Solve by completing square method.
px2 + qx + r = 0
Sol.
px2 + qx + r = 0
Dividing by p throughout
ii.
Find the solution Set and check it.
iii.
Eliminate 't' from
Subtracting (iv) from (iii)
OR
Eliminate 'x' from
Taking cube of eq. ----------------(i)
;
Taking square of eq. ----------(ii)
By comparing eq. (iii) & eq. (iv)
a6 – 3a2 = b6
– 2
Eliminant.
iv.
Find the relation of independent of 'x' for the
following equations.
X2 – 2X + 1 = 0
;
-X2 + 3X + m = 0
X2 – 2X + 1 = 0------------------(i)
-X2 + 3X + m = 0----------------(ii)
Sol.
       1
-2
L
1
-2 L
1
3
M
-1
3 M
v.
If
Sol.
S =
---------------------(i)
From
eq.
(i)
by componendo – dividendo theorem
By invertendo theorem
vi.
If
vi.
The marks obtained by the students in the subject
of English are given below. Find median of their marks.
Sol.
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Marks obtained
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Frequency
|
C.F
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Class boundries
|
Median Class
|
|
15 – 19
|
9
|
9
|
14.5 – 19.5
|
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20 – 24
|
18
|
9 + 18 = 27
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19.5 – 24.5
|
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25 – 29
|
35
|
27 + 35 = 62
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24.5 – 29.5
|
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30 – 34
|
17
|
62 + 17 = 79
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29.5 – 34.5
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35 – 39
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5
|
79 + 5 = 84
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34.5 – 39.5
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viii.
A set of data contains the value as 148, 145, 160,
157, 156, 160. show that
mode > median > mean.
Sol.
Mode =160---------------------(i)
For median arranging data in ascending order 145,
148, 156, 157, 160,
160. no. of values
= 6 (even no)
ix.
Find the variance and standard deviation from the
following information.
x.
Prove that
OR
xi.
Solve the following triangle if m<B = 900,
m>A = 600, and a = 6cm
xii.
Find the solution set and represent on the number
line.
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