Grade: 11
Full marks: 75
Time: 3 hours
Attempt all the questions
Group A (1 × 11 = 11)
Rewrite the correct
option in your answer sheet
1. Which of the
following is a statement?
(a) The fishes are beautiful
(b) Study mathematics.
(c) x is a capital of country y
(d)
Water is essential for health
(a) -20
(b) -20i
(c) 20i
(d) 20
3. If ÐC =
600, b = 5 cm and a = 4 cm of DABC,
what is the value of c?
(a) 3.58 cm
(b)
4.58 cm
(c) 4.89 cm
(d) 4.56
4. In a triangle ABC,
B =120o, a = 1, c = 1 then the other angles and sides are
(a) 35, 45, 2
(b) 10, 50, 3
(c) 20, 40, 2
(d) 30,
30, 3
5. The cosine of the
angle between the vectors 𝑎
= i − 2j + 3𝑘
and 𝑏 = i + 3j+ 3𝑘
is
(a) 1/14
(b) 14
(c)
(d) 196
Note: Option does not match as per the question, so the correct answer is
6. The equation of
parabola with the vertex at the origin and the directory y - 2 = 0
(a) x2 –
8y = 0
(b) y2 + 8y = 0
(c) x2
+ 8y = 0
(d) y2 - 8y = 0
7. A mathematical problem is given to three students Sumit, Sujan and Rakesh whose chance of solving it are 1/2 ,1/3, and 1/a respectively. The probability that the problem is solved is 3/4. The possible values of a are:
(a)
(b) 4
(c)
(d)
8. is equal to
(a) 0
(b) ∞
(c) 1
(d) 0
(a)
(b)
(c)
(d)
10. By Newton’s
Raphson, the positive root of x3 -18 = 0 in (2, 3) is
(a)2. 666
(b)
2.621
(c) 2.620
(d) 2.622
11. Two forces acting
at an angle of 45o have a resultant equal to N, if one of the forces be
N, what is the other force.
(a) 1N
(b) 2N
(c) 3N
(d) 4N
OR
The total cost
function of a producer is given as . What is the marginal cost (MC) at Q = 4 is
(a) Rs.38
(b)
Rs.34
(c) Rs.30
(d) Rs.28
Group B
12. A function f(x) =
x2 is given. Answer the following question for the function f(x).
(i) What is the
algebraic nature of the function?
·
The Algebraic Nature of the Function is
Quadratic.
(ii) Write the name
of the locus of the curve.
·
Parabola is the name for locus of the curve.
(iii) Write the
vertex of the function.
·
Vertex of function is (0,0).
(iv)Write any one
property for sketching the curve.
·
The Property of the given function are:
§
Function is Even.
§
Function is Symmetric about x-axis.
(v) Write the domain
of the function.
· The function is defined for all the value of x that belongs to the real number. So it’s domain is (-∞,∞).
13. Compare the sum
of n terms of the series: 1 + 2a +3a2 +4a3 +……….and a+ 2a
+ 3a+ 4a …up to n terms.
Series 1st:
1 + 2a +3a2 +4a3
+……….
It is an arithmetico-geometric
series.
Sn= 1 + 2a +3a2 +4a3
+……….+nan-1
aSn= a + 2a2 +3a3
+4a4 +……….+nan
Subtracting above equations
(1-a)Sn = 1+a+a2+a3+…………+an-1-nan
Series 2nd: a+ 2a + 3a+ 4a … up to n
terms
It is arithmetic series.
Let Sn = a+ 2a + 3a+ 4a … na
=
=
=
=
14.a)
In any triangle, prove that:
We Know
b+c =2R SinB + 2R
SinC
=2R(SinB
+ SinC )
--------------(i)
And
a =2R
SinA
=2R
Sin (1800-(B+C))
=2R
Sin (B+C))
---------------(ii)
Dividing above equations
14. b) Express= (4, 7) as the linear combination of
= (5, - 4) and
= (-2, 5).
15. Calculate the appropriate measure of Skewness for the data below.
Ans: The given distribution is not an open ended. It will be better to use Karl person's Coefficient Method.
15. Calculate the appropriate measure of Skewness for the data below.
Class | 0-10 | 10-20 | 20-30 | 30-40 | 40-50 | 50-60 |
---|---|---|---|---|---|---|
No of Workers | 10 | 12 | 25 | 35 | 40 | 50 |
Class | Mid Value (x) | No. Of Workers | d' = (x-25)/10 | fd' | fd'2 | c.f. |
---|---|---|---|---|---|---|
0-10 | 5 | 10 | -2 | -20 | 40 | 10 |
10-20 | 15 | 12 | -1 | -12 | 12 | 22 |
20-30 | 25 | 25 | 0 | 0 | 0 | 47 |
30-40 | 35 | 35 | 1 | 35 | 35 | 82 |
40-50 | 45 | 40 | 2 | 80 | 160 | 122 |
50-60 | 55 | 50 | 3 | 150 | 450 | 172 |
N=172 | Σ fd'=233 | Σ fd'2=697 |
We Know
16. Define different types of discontinuity of a function. Also write the condition for increasing, decreasing and concavity of function.
First Part:
A discontinuous function may be of following types:
- If
does not exists i.e.,
then the function is said to have an ordinary discontinuity.
Second Part:
Function |
Condition |
Increasing Function |
f’(x)>0 |
Decreasing Function |
f’(x)<0 |
Concavity i.
Concave Upward ii.
Concave Downward |
f’’(x)>0 f’’(x)<0 |
17) Evaluate:
Ans:
and
. Thus,
18. Define
Trapezoidal rule. Evaluate using Trapezoidal rule for, n=4.
Ans:
Trapezoidal rule:
If a function f is continuous on the closed interval [a,b],
then
Where the closed interval [a, b] has been
portioned into n sub intervals [x0, x1], [x1, x2],
……[xn-1, xn], each of the length .
Second Part
Since n=4, h = =
=0.25 and the five
points to be considered are x0 = 0, x1=0.25, x2
= 0.5, x3 = 0.75, x4
= 1. Evaluating the values of the functions at these points:
End Points |
x0 = 0 |
x1=0.25 |
x2 = 0.5 |
x3 = 0.75 |
x4 = 1 |
y= |
1 |
0.8 |
0.66666 |
0.57143 |
0.50000 |
Now, From trapezoidal rule,
=
[y0+ y1 +2y2 + 2y3
+ y4]
=[1+ 2*0.8 + 2*0.66666 +2*0.57143+0.50000]
=0.1250*5.57618
=0.69702
19. State sine law
and use it to prove Lami’s theorem.
Ans:
Sine Law:
In any triangle ABC,
Lami’s Theorem:
If three forces acting at a
point, be in equilibrium, each force is proportional to the sine angle between
the other two.
Let P, Q and R be three forces
acting at equilibrium at point O, represented as OA, OB, and OD respectively. Complete
the Parallelogram OACB in which diagonal OC represents the resultant of forces
P and Q represented by OX will be valanced by force R. That is, the force
represented by OC is equal and opposite to force R. So, CO represents the force
R. Since AC and OB are equal and parallel, so AC represent the force Q.
In triangle OAC, Using Sine Law
Also,
sin OCA =sin COB = sin (180-QOR) = sin QOR
sin COA = sin (180-ROP) = sin ROP
sin OAC = sin (180-POQ) = sin POQ
Thus,
OR
A decline in the
price of good X by Rs. 5 causes an increase in its demand by 20 units to 50
units. The new price is X is 15. (i) Calculate elasticity of demand. (ii) The
elasticity of demand is negative, what does it mean?
Ans:
Given:
ΔP= -Rs5, Q1 = 20units, Q2=50
units, P2 = Rs. 15
Then,
ΔQ = Q2-Q1 =50-20 =30 units
And P1=P2-ΔP = 15- (-5) =Rs.20
i.
Elasticity of demand:
ii. The elasticity of demand is negative means there is inverse relationship between price and quantity demand i.e., demand will increase when the prices decreases and demand will decrease and demand will decrease when price increases.
20. a The factors of the expressionHere:
.
(ii) Prove that = 0, where n is integer.
20.(b) Verify that: |x+y|
≤|x|+|y| Where x= 2 and y= -3.
Here, x=2 and y= -3
|x+y|=|2-3|=|-1|=1
|x|+|y|= |2|+|-3|=2+3=5
∴|x+y| ≤|x|+|y|
21. (a) The single
equation of pair of lines is 2x2 +3xy +y2 +5x +2y -3 = 0
(i) Find the equation
of pair straight lines represented by the single equation.
Given:
2x2 +3xy +y2 +5x +2y -3 = 0 -----------------(i)
Or, y2 +(3X+2)y+(2X2+5x-3) = 0
Which is quadratic in y so,
Taking -ve sign:
Taking +ve Sign:
Thus Separate Equations are :
2x+y-1=0...............................(2)
x+y+3=0...............................(3)
(ii) Are the pair of
lines represented by the given equation passes through origin? Write with
reason.
The pair of line represented by the given equations does not pass through the origin because the given equations is not homogenous.
(iii) Find the point
of intersection of the pair of lines.
-x+y+3=0_
x-4=0
or,
x=4.
Again,
From (3)
4+y+3=0
Or,
y=-7
Thus, point of intersection is (4,7).
21. (b) If three
vectors
are
mutually perpendicular unit vectors in space then write a relation between them.
Ans:
If three vectors
are mutually perpendicular unit vectors in the
space then
22. (i) Distinguish between derivative and anti-derivative of a function. Write their physical meanings and illustrate with example in your context. Find, the differential coefficient of log (Sin x) with respect to x.
Ans:
Derivative |
Antiderivative |
It gives the
slope of the function f(x). |
It gives the area under the curve of the function f(x). |
The
Derivative of Function is denoted by |
The anti-derivative of a function, denoted by ∫f(x)dx |
The derivative is defined as eh instantaneous rate of change
of the function at the given point. For example, the instantaneous velocity
v(t) is the derivative of the position function s(t).
That is, v(t) = s'(t). Furthermore, the acceleration a(t) is the derivative of the velocity v(t), i.e. a(t)=v'(t).Now suppose we are given an acceleration function a(t), but not the velocity function v(t) or the position function s(t). since a(t)=v'(t) determining the velocity function requires us to find an antiderivative of the acceleration function. Then, since v(t)=s'(t) determining the position function requires us to find the antiderivative of the velocity function.
Let y=log (sin x)
Differentiating both sides with respect to x.
(ii) Find the area
bounded by the y – axis, the curve x2 = 4 (y - 2) and the line y = 11.
Ans:
Here,
x2=4(y-2)
or,
The Curve x2=4(y-2) Meets the y-axis at the point
where x=0.
So, 4(y-2) =0
Or, y=2.
Now,
Hence, area of the curve is 36 square unit.