# 10th Maths Paper Solutions Set 1 : CBSE Delhi Previous Year 2012

General instructions:
1. All questions are compulsory.
2. The question paper consists of 34 questions divided into four sections A, B, C and
D.
3. Section A contains 10 questions of 1 mark each, which are multiple choices type
questions, Section B contains 8 questions of 2 marks each, Section C contains 10
questions of 3 marks each, Section D contains 6 questions of 4 marks each.
4. There is no overall choice in the paper. However, internal choice is provided in one
question of 2 marks, 3 questions of 3 marks each and two questions of 4 marks each.
5. Use of calculators is not permitted.
Q1 :

If 1 is a root of the equations ay2 + ay + 3 = 0 and y2 + y + b = 0 then ab equals:

A. 3

B. C. 6

D. −3

The given equations are ay2 + ay + 3 = 0 and y2 + y + b = 0

Given, 1 is the root of both the equations.

y= 1 will satisfy both these equations.

Putting y = 1 in ay2 + ay + 3 = 0, we get Putting y = 1 in y2 + y + b = 0, we get Thus, the value of ab is 3.

Hence, the correct answer is A.

Q2 :

The sum of first 20 odd natural numbers is:

A. 100

B. 210

C. 400

D. 420

Odd natural numbers are in the pattern 1, 3, 5, 7, 9…,.

These numbers form an A.P. where a = 1, d = 3 − 1 = 2

We know that,  Thus, the sum of first 20 odd natural numbers is 400.

Hence, the correct answer is C.

Q3 :

In Fig. 1, the sides AB, BC and CA of a triangle ABC, touch a circle at P, Q and R respectively. If PA = 4 cm, BP = 3 cm and AC = 11 cm, then the length of BC (in cm) is: A. 11

B. 10

C. 14

D. 15

Given, AP = 4 cm, BP = 3 cm and AC = 11 cm.

The lengths of tangents drawn from an external point to the circle are equal.

AP = AR, BP = BQ, CQ = CR …….. (1)

AC = 11 cm

AR + RC = 11 cm

AP + CQ = 11 cm [From equation (1)]

4 cm + CQ = 11 cm

CQ = (11 − 4) cm

CQ = 7 cm

BP = BQ = 3 cm

Now, BC = BQ + QC

BC = (3 + 7) cm

BC = 10 cm

Hence, the correct option is B.

Q4 :

In Fig 2, a circle touches the side DF of ΔEDF at H and touches ED and EF produced at

K and M respectively. If EK = 9 cm, then the perimeter of ΔEDF (in cm) is: A. 18

B. 13.5

C. 12

D. 9

Q5 :

If the radius of the base of a right circular cylinder is halved, keeping the height the same, then the ratio of the volume of the cylinder thus obtained to the volume of original cylinder is:

A. 1 : 2

B. 2 : 1

C. 1 : 4

D. 4 : 1

Q6 :

If the area of a circle is equal to sum of the areas of two circles of diameters 10 cm and 24 cm, then the diameter of the larger circle (in cm) is:

A. 34

B. 26

C. 17

D. 14

Q7 :

The length of shadow of a tower on the plane ground is times the height of the tower.

The angle of elevation of sun is:

A. 45°

B. 30°

C. 60°

D. 90°

Q8 :

If the coordinates of one end of a diameter of a circle are (2, 3) and the coordinates of its centre are (−2, 5), then the coordinates of the other end of the diameter are:

A. (−6, 7)

B. (6, −7)

C. (6, 7)

D. (−6, −7)

Q9 :

The coordinates of the point P dividing the line segment joining the points A (1, 3) and B (4, 6) in the ratio 2 : 1 are:

A. (2, 4)

B. (3, 5)

C. (4, 2)

D. (5, 3)

Q10 :

Two dice are thrown together. The probability of getting the same number on both dice is:

A. B. C. D. Q11 :

Find the value(s) of k so that the quadratic equation x2 − 4kx + k = 0 has equal roots.

Q12 :

Find the sum of all three digit natural numbers, which are multiples of 11.

Q13 :

Tangents PA and PB are drawn from an external point P to two concentric circles with centre O and radii 8 cm and 5 cm respectively, as shown in Fig. 3. If AP = 15 cm, then find the length of BP. Q14 :

In Fig. 4, an isosceles triangle ABC, with AB = AC, circumscribes a circle. Prove that the point of contact P bisects the base BC. OR

In Fig. 5, the chord AB of the larger of the two concentric circles, with centre O, touches the smaller circle at C. Prove that AC = CB. Q15 :

The volume of a hemisphere is . Find its curved surface area. Q16 :

In Fig. 6, OABC is a square of side 7 cm. If OAPC is a quadrant of a circle with centre O, then find the area of the shaded region.  Q17 :

If a point A (0, 2) is equidistant from the points B (3, p) and C (p, 5), then find the value of p.

Q18 :

A number is selected at random from first 50 natural numbers. Find the probability that it is a multiple of 3 and 4.

Q19 :

Solve for x: 4x2 − 4ax + (a2b2) = 0

OR

Solve for x: Q20 :

Prove that the parallelogram circumscribing a circle is a rhombus.

OR

Prove that opposite sides of a quadrilateral circumscribing a circle subtend supplementary angles at the centre of the circle.

Q21 :

Construct a right triangle in which the sides, (other than the hypotenuse) are of length 6 cm and 8 cm. Then construct another triangle, whose sides are times the corresponding sides of the given triangle.

Q22 :

In Fig. 7, PQ and AB are respectively the arcs of two concentric circles of radii 7 cm and

3.5 cm and centre O. If POQ = 30°, then find the area of the shaded region.  Q23 :

From a solid cylinder of height 7 cm and base diameter 12 cm, a conical cavity of same height and same base diameter is hollowed out. Find the total surface area of the remaining solid. OR

A cylindrical bucket, 32 cm high and with radius of base 18 cm, is filled with sand. This bucket is emptied on the ground and a conical heap of sand is formed. If the height of the conical heap is 24 cm, then find the radius and slant height of the heap.

Q24 :

The angles of depression of two ships from the top of a light house and on the same side of it are found to be 45° and 30°. If the ships are 200 m apart, find the height of the light house.

Q25 :

A point P divides the line segment joining the points A (3, −5) and B (−4, 8) such that . If P lies on the line x + y = 0, then find the value of K.

Q26 :

If the vertices of a triangle are (1, −3), (4, p) and (−9, 7) and its area is 15 sq. units, find the value(s) of p.

Q27 :

A box contains 100 red cards, 200 yellow cards and 50 blue cards. If a card is drawn at random from the box, then find the probability that it will be (i) a blue card (ii) not a yellow card (iii) neither yellow nor a blue card.

Q28 :

The 17th term of an AP is 5 more than twice its 8th term. If the 11th term of the AP is 43, then find its nth term.

Q29 :

A shopkeeper buys some books for Rs 80. If he had bought 4 more books for the same amount, each book would have cost Rs 1 less. Find the number of books he bought.

OR

The sum of two numbers is 9 and the sum of their reciprocals is . Find the numbers.

Q30 :

Sum of the first 14 terms of an AP is 1505, and its first term is 10. Find its 25th term.

Q31 :

Prove that the tangent at any point of a circle is perpendicular to the radius through the point of contact.

OR

A quadrilateral ABCD is drawn to circumscribe a circle. Prove that AB + CD = AD + BC.

Q32 :

A solid is in the shape of a cone surmounted on a hemisphere, the radius of each of them being 3.5 cm and the total height of solid is 9.5 cm. Find the volume of the solid. Q33 :

A bucket is in the form of a frustum of a cone and it can hold 28.49 litres of water. If the radii of its circular ends are 28 cm and 21 cm, find the height of the bucket. 