Tag: calculations and mental strategies 1

Questions Related to calculations and mental strategies 1

An algebraic expression, $11-y$ can be written in the statement form as  ____ 

maths calculations and mental strategies 1 equations from statements forming equations from statements writing mathematical statements

  1. $11$ less than $y$

  2. $y$ less than $11$

  3. $y$ more than $11$

  4. $y$ divided by $11$

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Correct Option: B
Explanation:
$y$  less than $11$

If fives of a number is $80$, then the number is ___ 

maths calculations and mental strategies 1 equations from statements forming equations from statements writing mathematical statements

  1. $-16$

  2. $1$

  3. $16$

  4. $40$

Show answer
Correct Option: C
Explanation:
Let $x$ be a number.
$\Rightarrow\,5x=80$
$\Rightarrow\,x=\dfrac{80}{5}=16$
$\therefore\,x=16$
The number is $16$

If a $\in { 1,2,3,4 } ,$ then number of equations of the form $x ^ { 2 } + a x + 1 = 0$ having real roots is

maths calculations and mental strategies 1 equations from statements forming equations from statements writing mathematical statements

  1. $1$

  2. $2$

  3. $3$

  4. $4$

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Correct Option: C

The difference between a two-digit number and the number obtained by interchanging the positions of its digits is 36. What is the difference between the two digit of that number ?

maths calculations and mental strategies 1 equations from statements forming equations from statements writing mathematical statements

  1. 3

  2. 4

  3. 9

  4. Cannot be determined

  5. None of these

Show answer
Correct Option: B
Explanation:
Let the ten's digit be $x$ and unit's digit be $y$.

Then, $(10x + y) - (10y + x) = 36$

$9(x - y) = 36$

$x - y = 4$

Therefore, the difference between the two digit of that number is $4$

The sum of the digit of a two-digit number is $\frac { 1 }{ 5 } $ of the difference between the number and the number obtained by interchanging the positions of the digit. What is definitely the difference between the digit of that number ?

maths calculations and mental strategies 1 equations from statements forming equations from statements writing mathematical statements

  1. 5

  2. 7

  3. 9

  4. Data inadequate

  5. None of these

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Correct Option: A

The sum of the digits of a two-digit number is 9 less then the number. Which of the following digits is at unit's place of the number ?

maths calculations and mental strategies 1 equations from statements forming equations from statements writing mathematical statements

  1. 1

  2. 2

  3. 4

  4. Data inadequate

Show answer
Correct Option: A
Explanation:
Let $x,y$ are the digits of a number. Then the number $= 10x+y$

as per condition : $10x+y-9 = x+y$

Then as per the given problem,

$x+y=10x+y-9$

or, $9x=9$

or, $x=1$

So, we can say that for any value of y from 1 to 9, the condition satisfies.

for eg: if the number is 18

18–9 = 1+8

9=9 , satisfied.


So the tenth's place digit is $1$.

Get the algebraic expression in the following cases using variables, constant and arithmetic operations.
Subtraction of $z$ from $y$.

maths calculations and mental strategies 1 equations from statements forming equations from statements writing mathematical statements

  1. $y+z$

  2. $y-z$

  3. $z-y$

  4. $None\ of\ these$

Show answer
Correct Option: B
Explanation:

Subtraction of $z$ from $y$ implies that a number of value $z$ is to be subtracted from another number of $y$ value $y$ which means $y-z$.

Two years ago the mean age of $40$ people was $11$ years. Now a person left the group and the mean age is changed to $12$ years, then the age of the person who left the group is?

maths calculations and mental strategies 1 equations from statements forming equations from statements writing mathematical statements

  1. $52$ years

  2. $48$ years

  3. $54$ years

  4. None of these

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Correct Option: A

Five years ago Anjali's age was twice Sarita's age. Five years hence, their ages will be $4 : 3$. Anjali's present age is 

maths calculations and mental strategies 1 equations from statements forming equations from statements writing mathematical statements

  1. $15$ years

  2. $10$ years

  3. $12$ years

  4. $16$ years

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Correct Option: A

Kiran is 24 years older than Rakesh. 10 years back Evans age was five times the age of Rakesh. Find the present age of Rakesh.

maths calculations and mental strategies 1 equations from statements forming equations from statements writing mathematical statements

  1. $40 years $

  2. $16 years$

  3. $20 years$

  4. $36 years

Show answer
Correct Option: A