Tag: maths

Questions Related to maths

If the sector of a circle of diameter $14 cm$ subtends an angle of $30^{\circ}$ at the centre, then its area is

  1. $49 \pi$

  2. $\displaystyle \frac{49 \pi}{12}$

  3. $\displaystyle \frac{242}{3\pi}$

  4. $\displaystyle \frac{121}{3\pi}$


Correct Option: B,D
Explanation:

Area of a sector $=\dfrac{\theta}{360^0} \times \pi r^2 =\dfrac{30}{360} \times \pi (7)^2 = \dfrac{49 \pi}{12}$


Also, 
$ \dfrac{121}{3\pi}=\dfrac{121 \times 7}{3 \times 22} = \dfrac{49 \times 22}{12 \times 7} = \dfrac{49 \pi}{12}$

A circular disc of radius 10 cm is divided into sectors with  angles $120^{\circ}$ and $150^{\circ}$ then  the ratio of the area of two  sectors is

  1. 4 : 5

  2. 5 : 4

  3. 2 : 1

  4. 8 : 7


Correct Option: A
Explanation:

Area of sector formed from angle $\theta$ = $\frac{\theta}{260} \pi r^2$, where r is the radius of the circle
Now, if angle is 120, 150 then the ratio of area of sector will be:
= $\frac{\frac{120}{360} \pi r^2}{\frac{150}{360} \pi r^2}$
= $\frac{120}{150}$ = 4:5

The area of a sector of a circle of angle $\displaystyle 60^{\circ}$ is $\displaystyle \frac{66}{7}cm^{2}$ then the area of the corresponding major sector is

  1. $\displaystyle 14cm^{2}$

  2. $\displaystyle \frac{55}{7}cm^{2}$

  3. $\displaystyle \frac{110}{7}cm^{2}$

  4. $\displaystyle \frac{330}{7}cm^2$


Correct Option: D
Explanation:

Area of a sector of a circle of radius 'r' and angle  $ \theta = \frac {

\theta  }{ 360 } \pi {r}^{2}$
Given, $ \frac { 60 }{ 360 } \times \frac {22}{7} \times {r}^{2} = \frac {66}{7}  {cm}^{2} $

$ {r}^{2} = 18 $
Now, area of sector with angle {300}^{o} $ = \frac

{ 300 }{ 360 } \times \frac {22}{7} \times {r}^{2} = \frac

{ 300 }{ 360 } \times \frac {22}{7} \times 18 = \frac {330}{7}  {cm}^{2} $




A Car has two wipers which do not cover mutual area. Length of each wiper is 25 cms and it makes angle of $\displaystyle 115^{\circ}$ while cleaning. The area of cleaning by the wiper in one movement will be-

  1. $\displaystyle \frac{152815}{126}cm^{2}$

  2. $\displaystyle \frac{185125}{128}cm^{2}$

  3. $\displaystyle \frac{215815}{126}cm^{2}$

  4. $\displaystyle \frac{158125}{126}cm^{2}$


Correct Option: D
Explanation:

Required area $\displaystyle =2\times \frac{115^{\circ}}{360^{\circ}}\pi \left ( 25 \right )^{2}$
$\displaystyle =2\times \frac{115}{360}\times \frac{22}{7}\times 625$


$\displaystyle=\frac{158125}{126}cm^{2}$

What is the volume (in cm$^3$)of the container which can hold 5.28 litres of oil?

  1. V = 5.28 cm$^3$

  2. V = 52.8 cm$^3$

  3. V = 528 cm$^3$

  4. V = 5280 cm$^3$


Correct Option: D
Explanation:

$1ℓ=1000\quad { cm }^{ 3 }\ 5.28ℓ=5.28\times 1000\quad { cm }^{ 3 }\ \quad \quad \quad \quad =5280\quad { cm }^{ 2 }$

so D is the correct option

$0.002\times 0.5=$?

  1. $0.0001$

  2. $0.001$

  3. $0.01$

  4. $0.1$


Correct Option: B
Explanation:

$2\times 5=10$.
Sum of decimal places $= 4$
$\therefore 0.002\times 0.5=0.001$

Which of the following is equal to $3.14\times { 10 }^{ 6 }$?

  1. $314$

  2. $3140$

  3. $3140000$

  4. None of these


Correct Option: C
Explanation:

$3.14\times { 10 }^{ 6 }=3.14\times 1000000=3140000$

Evaluate the following up to three decimal places:

$A)\dfrac{0.1}{0.03}$

$B)\dfrac{1.1}{1.5}$

  1. $3.333,0.733$

  2. $3.733,0.733$

  3. $3.333,3.733$

  4. $7.333,0.733$


Correct Option: A
Explanation:

$A)\dfrac{0.1}{0.03}=\dfrac{10}{3}=3.333$


$B)\dfrac{1.1}{1.5}=\dfrac{11}{15}=0.733$

Which is the greatest number in the following

  1. $16\frac{2}{3}\% $

  2. $\frac{2}{{15}}$

  3. $\frac{1}{{11}}$

  4. $0.17$


Correct Option: D
Explanation:
$16 \dfrac 2 3 \% ; \dfrac{2}{15} ; \dfrac{1}{11} ; 0.17$

$\Rightarrow \dfrac{50}{3} \times \dfrac{1}{100} ; \dfrac{2}{15} ; 0.0909.... ; 0.17$

$\Rightarrow \dfrac{1}{3 \times 2} ; 0.1333 ; 0.0909 .... ; 0.17$

$\Rightarrow 0.1666...7 ; 0.1333 ; 0.0909 ; 0.17$

$\therefore 0.17$ is greater 

If the fractions $\cfrac{3}{5}$,$\cfrac{2}{11}$, $\cfrac{4}{7}$, $\cfrac{1}{3}$, $\cfrac{5}{6},$ and $\cfrac{3}{8}$are arranged in the ascending order which fraction will be at the 3rd place ?

  1. $\cfrac{1}{3}$

  2. $\cfrac{3}{5}$

  3. $\cfrac{2}{11}$

  4. $\cfrac{3}{8}$


Correct Option: D
Explanation:

LCM of the denominators of given rational numbers i.e. 5, 11, 7, 3, 6, and 8 = 9240

Now by equating the denominators we get, 
$\dfrac { 3 }{ 5 } =\dfrac { 5652 }{ 9240 }$

$\dfrac { 2 }{ 11 } =\dfrac { 1680 }{ 9240 }$

$\dfrac { 4 }{ 7 } =\dfrac { 5280 }{ 9240 }$

$\dfrac { 1 }{ 3 } =\dfrac { 3080 }{ 9240 }$

$\dfrac { 5 }{ 6 } =\dfrac { 7700 }{ 9240 }$

$\dfrac { 3 }{ 8 } =\dfrac { 3465 }{ 9240 }$
 On seeing the rational numbers it is clear that the rational number at third position in ascending order is $\dfrac { 3465 }{ 9240 } \  i.e.\dfrac { 3 }{ 8 }$
So, correct answer is option D.