Tag: maths

Questions Related to maths

If $(30 + x) : (23 + x) = 5 : 4$ then find the value of x.

  1. 5

  2. 6

  3. 4

  4. 7


Correct Option: A
Explanation:

$ => 30 + x : 23 + x = 5:4 $


$ => \frac {30 + x}{23 + x} = \frac {5}{4} $

Cross multiplying, 

$ 120 + 4x = 115 + 5x $


$ 120 - 115 = 5x - 4x $


$ x = 5 $

Translate the following sentence into an algebraic equation: "13 diminished from twice a number is equal to 17"

  1. $2x-13=17$

  2. $13-2x=17$

  3. $2x-17=13$

  4. $2x+13=17$


Correct Option: A
Explanation:

Let  the  number  be  $x.$


Twice  of  the  number  is  $2x$  and  $13$  is  diminished  from  $2x$  means  $(2x-13)$  and  it  is  equal   to   $17. $
 So  answer  is  option  A

'8 is less than twenty times a' is written as 

  1. 8 - 20a

  2. 20ac

  3. 8 < 20 $\times$ a - 8

  4. 20a - 8


Correct Option: D
Explanation:

Eq : 20a - 8

Algebraic expression for the statement 8 times a taken away from 60 

  1. 8a - 60

  2. 60 - 8a

  3. 0

  4. 60a - 8


Correct Option: B
Explanation:

Eq : 20a - 8

The equation for the statement : 'half of a number added to 20 is 25' 

  1. $\displaystyle{\frac{x}{4}}$ + 20 = 25

  2. $\displaystyle{\frac{x}{5}}$ + 25 = 20

  3. $\displaystyle{\frac{x}{2}}$ + 20 = 25

  4. $\displaystyle{\frac{x}{3}}$ + 20 = 25


Correct Option: C
Explanation:

$\displaystyle{\frac{x}{2}}$ + 20 = 25 

Half of the number added to 20 will give the answer 25
$\dfrac{10}{2} +20=25$

Equation of the statement : 'Thrice the length of a room is $240$ metres.' 

  1. $3l = 240$

  2. $3 + l = 40$

  3. $3l = 420$

  4. None of these


Correct Option: A
Explanation:

Let $l$ be the length of a room 

therefore according to statement, required equation is   
$3l = 240 $

Equation for the statement: 'thrice the length (L) of a room is 340 metres'

  1. $3L = 43$

  2. $3L = 340$

  3. $3 + L= 34$

  4. None of these


Correct Option: B
Explanation:

$\Rightarrow$  The length of room is $L.$

$\Rightarrow$  So, thrice the length means $3L.$

The equation for thrice the length of the room is $340 \ meters$

$\Rightarrow$  $3L=340\ meters.$

The equation for the statement:"half a number added to 10 is 15".

  1. $\dfrac{X}{2}\,+ 10\,+ 5$

  2. $\dfrac{X}{2}\,+ 10\,= 5$

  3. $\dfrac{X}{2}\,+ 15\,= 10$

  4. $\dfrac{X}{2}\,= -10\,+ 15$


Correct Option: D
Explanation:

Let the number be $X.$

Half of the number is $\dfrac{X}{2}$
Half a number added to $10$ is $\dfrac{X}{2}+10$
So, according to the question,
$\Rightarrow$  $\dfrac{X}{2}+10=15$

$\Rightarrow$  $\dfrac{X}{2}=-10+15$

In three coloured boxes - Red, Green and Blue, $108$ balls are placed. There are twice as many balls in the green and red boxes combined as there are in the blue box and twice as many in the blue box as there are in the red box. How many balls are there in the green box?

  1. $18$

  2. $36$

  3. $45$

  4. None of these


Correct Option: D

The following expressions in statement is given as:
$x+3$

3 is added to x

  1. True

  2. False


Correct Option: A
Explanation:

Yes the  statement is correct. This defines the expression in words.