ICSE Class 9 Maths Sample Question Paper 9 with Answers

Section – A
(Attempt all questions from this Section)

Question 1.
(a) Find xy, if x + y = 6 and x – y = 4.
Answer:
Given: x + y =6,x – y=4.
Now, 4xy =(x+y)2-(x-y)2
= 62 – 42
=20
xy=\(\frac{20}{4}\)=5.

ICSE Class 9 Maths Sample Question Paper 9 with Answers

(b) Find the mean of first 10 prime numbers.
Answer:
First lo prime numbers are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29
∴ ∑ =129,n=10
Mean = \(\frac{\sum x}{n}=\frac{129}{10}=12.9\)

(c) If x = acosθ + bsinθ and y = asinθ – bcosθ, prove that x2 + y2 = a2 + b2.
Answer:
ICSE Class 9 Maths Sample Question Paper 9 with Answers 10

ICSE Class 9 Maths Sample Question Paper 9 with Answers

Question 2.
(a) Simplify : \(\left(\frac{1}{\sqrt{5}-2}-\frac{1}{\sqrt{5}+2}\right)\left(\frac{1}{2+\sqrt{3}}+\frac{1}{2-\sqrt{3}}\right)\)
Answer:
ICSE Class 9 Maths Sample Question Paper 9 with Answers 11
(b) The area of a trapezium is 540 cm2. If the ratio of parallel sides is 7 : 5 and the distance between them is 18 cm, find the length of parallel sides.
Answer:
Given : Area of trapezium = 510 cm2
Perpendicular distance between parallel lines = 18 cm
Ratio of parallel sides = 7 : 5
Let the length of parallel sides be 7x and 5x.
Area of trapezium = \(\frac{1}{2}\) (Sum of parallel sides) x Perpendicular distance
ICSE Class 9 Maths Sample Question Paper 9 with Answers 12
7x = 7 x 5 = 35
and 5x = 5 x 5 = 25
Hence, the length of parallel sides are 35 cm and 25 cm.

ICSE Class 9 Maths Sample Question Paper 9 with Answers

(c) Solve : (3x + 1) (2x + 3) = 3.
Answer:
(3x + 1) (2x + 3) = 3
6 x 2 + 9x + 2x + 3 – 3 = O
6 x 2 +11x = 0
x (6x + 11) = 0
x=0 or 6x+11=0
x = 0 or x=\(\frac{-11}{6}\)
x = 0 or \(\frac{-11}{6}\)

Question 3.
(a) Express \(\log _{10}\left(\frac{a^{3} c^{2}}{\sqrt{b}}\right)\)
A ladder 13 cm long rests against a vertical wall. If the foot of the ladder is 5 m from the foot of the in terms of log10 a, log10 b and log10 c.
Answer:
ICSE Class 9 Maths Sample Question Paper 9 with Answers 14

ICSE Class 9 Maths Sample Question Paper 9 with Answers

(b) A ladder 13 cm long rests against a vertical wall. If the foot of the ladder is 5 m from the foot of the wall, find the distance of the other end of the ladder from the ground.
Answer:
Let AC be the ladder and BC be the height of the wall.
Then, AC = 13m, AB= 15m, ∠B=90°
∴ By Pythagoras theorem,
ICSE Class 9 Maths Sample Question Paper 9 with Answers 15

(c) Factorize : a4 + b4 – 11a2 b2.
Answer:
ICSE Class 9 Maths Sample Question Paper 9 with Answers 16

Question 4.
(a) Simplify: \(\sqrt{\frac{1}{4}}+(0.04)^{-1 / 4}-(8)^{2 / 3}\)
Answer:
ICSE Class 9 Maths Sample Question Paper 9 with Answers 17

ICSE Class 9 Maths Sample Question Paper 9 with Answers

(b) In the figure, ABCD is a trapezium in which DA || CB. AB has been produced to E. Find the angles of the trapezium.
ICSE Class 9 Maths Sample Question Paper 9 with Answers 1
Answer:
Given: DA || CB
x + + 100 = 180° (Co-interior angles) … (i)
⇒ x+2y = 170°
Also, x + 25° = y (Corresponding angles) … (ii)
x – y= – 25°
Subtracting equation (ii) from equation (i), we get
3y = 195°
= \(y=\frac{195^{\circ}}{3}=65^{\circ}\)
Putting y = 65° in equation (ii), we get
X – 65° = – 25°
x = 65 – 25°=40°
∠A = x + 25° = 40°+ 25° = 65°
∠B = 180° – y= 180 – 650= 115°
∠C = 2y + 10° =2 x 65° + 10° = 1400
∠D = x = 40°

(c) Calculate the compound interest for the second year on ₹ 8000 when invested for 3 years at 10% p.a.
Answer:
ICSE Class 9 Maths Sample Question Paper 9 with Answers 18

Section – B
(Attempt any four questions from this Section)

Question 5.
(a) Solve for x : 25x – 1 = 52x – 1 – 100.
Answer:
ICSE Class 9 Maths Sample Question Paper 9 with Answers 19
ICSE Class 9 Maths Sample Question Paper 9 with Answers 20

ICSE Class 9 Maths Sample Question Paper 9 with Answers

(b) In a ΔABC, ∠A = 80°, ∠B = 40° and bisectors of ∠B and ∠C meet at O. Find ∠BOC.
Answer:
\frac{\sum x}{n}=\frac{129}{10}=12.9
ICSE Class 9 Maths Sample Question Paper 9 with Answers 21
ICSE Class 9 Maths Sample Question Paper 9 with Answers 22

(c) Without using tables, evaluate :
ICSE Class 9 Maths Sample Question Paper 9 with Answers 3
Answer:
ICSE Class 9 Maths Sample Question Paper 9 with Answers 23

ICSE Class 9 Maths Sample Question Paper 9 with Answers

Question 6.
(a) If x = 3 + 2√2 , find the value of \(x^{3}-\frac{1}{x^{3}}\)
Answer:
ICSE Class 9 Maths Sample Question Paper 9 with Answers 24

(b) Construct a rectangle each of whose diagonals measures 6 cm and the diagonals intersect at an angle of 45°.
Answer:
ICSE Class 9 Maths Sample Question Paper 9 with Answers 25
Given: Each diagonal = 6 cm, diagonals intersect at 45°.
Steps of construction:
(1) Draw diagonal AC = 6 cm.
(2) Bisect AC at O
(3) At O, draw ∠COX = 45° and extend XO to Y.
(4) From O, cut-off XY at D and B such that OD = OB = 3 cm,
i.e., BD = 6 cm.
(5) Join A, B, C, D to get the required rectangle ABCD.

ICSE Class 9 Maths Sample Question Paper 9 with Answers

(c) KM is a straight line of 13 units. If K has the coordinates (2, 5) and M has the coordinates (x, – 7), find the possible values of x.
Answer:
ICSE Class 9 Maths Sample Question Paper 9 with Answers 26

Question 7.
(a) If \(x=\frac{\sqrt{7}+1}{\sqrt{7}-1} \text { and } y=\frac{\sqrt{7}-1}{\sqrt{7}+1}\)find the value of \(\frac{x^{2}+x y+y^{2}}{x^{2}-x y+y^{2}}\)
Answer:
ICSE Class 9 Maths Sample Question Paper 9 with Answers 27
ICSE Class 9 Maths Sample Question Paper 9 with Answers 28

(b) In ΔABC, AC = 3 cm. If M is the mid-point of AB and a straight line through M parallel to AC cuts BC at N, what is the length of MN ?
ICSE Class 9 Maths Sample Question Paper 9 with Answers 4
Answer:
Given : AC = 3 cm, M is the mid-point of AB, MN || AC.
Since, M the mid-point of AB and MN || AC
Therefore, by mid-point theorem, we have
MN = \(\frac{1}{2}\)AC= \(\frac{1}{2}\) x 3cm = 1.5cm

ICSE Class 9 Maths Sample Question Paper 9 with Answers

(c) If θ is an acute angle and tan θ = \(\frac{5}{12}\), find the value of cosθ + cot θ.
Answer:
ICSE Class 9 Maths Sample Question Paper 9 with Answers 29
ICSE Class 9 Maths Sample Question Paper 9 with Answers 30

Question 8.
(a) Factorize : 1 – 2ab – (a2 + b2)
Answer:
ICSE Class 9 Maths Sample Question Paper 9 with Answers 31

ICSE Class 9 Maths Sample Question Paper 9 with Answers
(b) In the given figure, AOC is a diameter of a circle with centre O and arc A×B = \(\frac{1}{2}\) arc BYC. Find ∠BOC.
ICSE Class 9 Maths Sample Question Paper 9 with Answers 5
Answer:
ICSE Class 9 Maths Sample Question Paper 9 with Answers 32

(c) In a class of 90 students, the marks obtained in a weekly test were as under.
ICSE Class 9 Maths Sample Question Paper 9 with Answers 6
Construct a combined histogram and frequency polygon.
Answer:
ICSE Class 9 Maths Sample Question Paper 9 with Answers 33
ICSE Class 9 Maths Sample Question Paper 9 with Answers 34

ICSE Class 9 Maths Sample Question Paper 9 with Answers

Question 9.
(a) Divide ₹ 1,95,150 between A and B so that the amount that A receives in 2 years is the same as that of B receives in 4 years. The interest is compounded annually at the rate of 4% p.a.
Answer:
ICSE Class 9 Maths Sample Question Paper 9 with Answers 35
ICSE Class 9 Maths Sample Question Paper 9 with Answers 36
A’s share = 1,01,400.
and B’s share = (1,95,150 – 1,01,400) = ₹ 93,750.

ICSE Class 9 Maths Sample Question Paper 9 with Answers

(b) Solve simultaneously : \(\frac{3}{x+y}+\frac{2}{x-y}=3 ; \frac{2}{x+y}+\frac{3}{x-y}=\frac{11}{3}\)
Answer:
ICSE Class 9 Maths Sample Question Paper 9 with Answers 37
ICSE Class 9 Maths Sample Question Paper 9 with Answers 38
ICSE Class 9 Maths Sample Question Paper 9 with Answers 39

ICSE Class 9 Maths Sample Question Paper 9 with Answers

(c) If a = cz, b = ax and c = by, prove that xyz = 1.
Answer:
ICSE Class 9 Maths Sample Question Paper 9 with Answers 40

Question 10.
(a) If sin (A + B) = 1 and cos (A – B) = \(\frac{\sqrt{3}}{2}\), 0° < A + B ≤ 90°, A > B, then find A and B.
Answer:
sin (A + B) = 1 = sin 90°
A + B = 90°
cos (A – B) =\(\frac{\sqrt{3}}{2}\) = cos 30°
A – B = 30°
Adding (i) and (ii), we get
A + B + A – B = 90° + 30°
⇒ 2A = 120°
A = \(\frac{120^{\circ}}{2}\) = 60°
Putting A= 60° in (i), we get
60° + B = 90°
⇒ B = 90° – 60° = 30°
∴ A = 60°, B = 30°

ICSE Class 9 Maths Sample Question Paper 9 with Answers

(b) The sum of the digits of a two-digit number is 5. The digit obtained by increasing the digit in ten’s place by unity is one-eighth of the number. Find the number.
ICSE Class 9 Maths Sample Question Paper 9 with Answers 7
Answer:
Let the digit at ten’s place be  and that at unit’s place be y.
∴ The number = 10x + y
By 1st condition,
x + y = 5
By 2nd condition,
x + 1 = \(\frac{1}{8}\) (10x + y)
⇒ 8 (x + 1) = 10x + y
⇒ 8x + 8 = 10x + y
⇒ 2x + y = 8
Subtracting (i) from (ii), we get
x = 3.
Putting x = 3 in (i), we get
3 + y = 5
⇒ y = 5 – 3 = 2
The required number = 10x + y = 10 x 3 + 2 = 32

ICSE Class 9 Maths Sample Question Paper 9 with Answers

(c) Given, log10 x = a and log10 y =
(i) Write down 10a-1 in terms of x
(ii) Write down 102b in terms of y.
(iii) If log10 P = 2a-b, express P in terms of x and y.
Answer:
ICSE Class 9 Maths Sample Question Paper 9 with Answers 42

Question 11.
(a) Draw the graph of the equations 2x – 3y = 7 and x + 6y = 11 and find their solutions.
Answer:
ICSE Class 9 Maths Sample Question Paper 9 with Answers 43ICSE Class 9 Maths Sample Question Paper 9 with Answers 44
The two lines intersect each other at the point (5, 1).
∴ x = 5, y = 1

ICSE Class 9 Maths Sample Question Paper 9 with Answers

(b) In the figure, area of ΔABD = 24 sq. units. If AB = 8 units, find the height of ΔABC.
Answer:
Given : Area of A ABD = 24 sq. units, AB = 8 units, DC || AB.
Area of ΔABC = Area of ΔABD
(∵ They are on same base and between same parallels)
= 24 sq. units.
⇒ \(\frac{1}{2}\) x AB x Height of ΔABC = 24
⇒ \(\frac{1}{2}\) x 8 x Height of ΔABC = 24
⇒ Height of Δ ABC = \(\frac{24}{4}\) = 6 units.

(c) If x – y = 8 and xy = 20, evaluate : (i) x + y (ii) x2 – y2.
Answer:
Given x – y – 8, xy = 20.
(i) (x + y)2 = (x – y)2 + 4 xy = 82 + 4 x 20 = 64 + 80 = 144
x + y = ± √144 = ± 12
x2 – y2 = (x + y) (x – y)
= (± 12) x 8
= ± 96.

ICSE Class 9 Maths Question Papers with Answers

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