Tag: maths

Questions Related to maths

Sum of 10 and 40 is

maths operations adding and subtracting numbers using place value addition & subtraction mental additions and subtractions

  1. $20$

  2. $0$

  3. $50$

  4. $400$

Show answer
Correct Option: C
Explanation:

    1 0

 + 4 0
-----------
    5 0
So correct answer will be option C
   

Difference of $500$ and $200$ is

maths operations adding and subtracting numbers using place value addition & subtraction mental additions and subtractions

  1. $100$

  2. $300$

  3. $0$

  4. $1000$

Show answer
Correct Option: B
Explanation:

  5 0 0

- 2 0 0
-----------
   3 0 0
So the correct answer will be option B 

The difference between the largest 5-digit number and smallest 5-digit number is

maths operations adding and subtracting numbers using place value addition & subtraction mental additions and subtractions

  1. 90,000

  2. 89,999

  3. 109,999

  4. None

Show answer
Correct Option: B
Explanation:

 $99999$
$-10000$
______
$89999$

Two pipes X and Y can fill a cistern in 24 min. and 32 min. respectively. If both the pipes are opened together, then after how much time Y should be closed so that the tank is full in 18 minutes?

maths operations adding and subtracting numbers using place value addition & subtraction mental additions and subtractions

  1. 6 min

  2. 8 min

  3. 10 min

  4. None of these

Show answer
Correct Option: B
Explanation:

Let Y closed pipe after a min .
Then part filled by (X+Y) in a min +Part filled by X in (18-x) 
So $a(\frac{1}{24}+\frac{1}{32})+(18-a)\frac{1}{24}= 1$
Multy by 96 
Or 4a+3a+72-4a=96
Or 3x=24
Or x=8 min

If $\displaystyle x=\frac{4\sqrt{2}}{\sqrt{2}+1}$ then find the value of $\displaystyle \frac{1}{\sqrt{2}}\left ( \frac{x+2}{x-2}+\frac{x+2\sqrt{2}}{x-2\sqrt{2}} \right )$

maths operations adding and subtracting numbers using place value addition & subtraction mental additions and subtractions

  1. $\displaystyle \sqrt{2}$

  2. $12+8\displaystyle \sqrt{2}/5$

  3. $12-8\displaystyle \sqrt{2}$

  4. $\displaystyle \frac{16\sqrt{2}+24}{5}$

Show answer
Correct Option: A
Explanation:

$x=\frac{4\sqrt{2}}{\sqrt{2+1}}$
$\frac{1}{\sqrt{2}}\left ( \frac{x+2}{x-2}+\frac{x+2\sqrt{2}}{x-2\sqrt{2}} \right )$
Put the value of x
$\frac{1}{\sqrt{2}}\left ( \frac{\frac{4\sqrt{2}}{\sqrt{2+1}}+2}{\frac{4\sqrt{2}}{\sqrt{2+1}}-2}+\frac{\frac{4\sqrt{2}}{\sqrt{2+1}}+2\sqrt{2}}{\frac{4\sqrt{2}}{\sqrt{2+1}}-2\sqrt{2}} \right )$
=$\frac{1}{\sqrt{2}}\left ( \frac{4\sqrt{2}+2\sqrt{2}+2}{4\sqrt{2}-2\sqrt{2}-2} \right )+\left ( \frac{4\sqrt{2}+4+2\sqrt{2}}{4\sqrt{2}-4-2\sqrt{2}} \right )$
=$\frac{6\sqrt{2}+2}{2\sqrt{2-2}}+\frac{6\sqrt{2}+4}{2\sqrt{2}-4}$
=$\frac{1}{\sqrt{2}}\left ( \frac{32-24\sqrt{2}}{16-12\sqrt{2}} \right )$
=$\sqrt{2}$

If P : Q : R = 6 : 5 : 4 and $\displaystyle P^{2}+Q^{2}+R^{2}=192500$ then find $\displaystyle \frac{(P+Q-R)}{2}$

maths operations adding and subtracting numbers using place value addition & subtraction mental additions and subtractions

  1. 175

  2. 165

  3. 185

  4. 200

Show answer
Correct Option: A
Explanation:

$
:Q:R\quad =\quad 6:5:4\ Let\quad P\quad \quad =\quad 6x\ Q=\quad 5x\ R\quad =\quad 4x\ { P }^{ 2 }+{ Q }^{ 2 }{ +\quad R }^{ 2 }\quad =\quad 192500\ { (6x) }^{ 2 }+{ (5x) }^{ 2 }+(4x)^{ 2 }\quad =\quad 192500\ 77{ x }^{ 2 }\quad =\quad 192500\ { x }^{ 2 }\quad =\quad 2500\ x\quad =\quad 50\ \ \frac { P+Q-R }{ 2 } \quad =\quad \frac { 6x+5x-4x }{ 2 } \quad =\quad \frac { 7x }{ 2 } \quad =\quad \frac { 7\times 50 }{ 2 } \quad =\quad 175
$

Given $5A9+3B7+2C8=1114$, then the maximum value of $C$ is

maths operations adding and subtracting numbers using place value addition & subtraction mental additions and subtractions

  1. $5$

  2. $7$

  3. $9$

  4. $none\ of\ these$

Show answer
Correct Option: C
Explanation:

  1  2
  5  A  9
  3  B  7
  2  C  8
1 1  1  4
$2+A+B+C=11$
$A+B+C=9$
Clearly max value of $C=9$

A 3-digit number 4a3 is added to another 3-digit number 984 to give the four-digit number 13b7 which is divisible by 11 Then (a + b) is

maths operations adding and subtracting numbers using place value addition & subtraction mental additions and subtractions

  1. 10

  2. 11

  3. 12

  4. 15

Show answer
Correct Option: A
Explanation:

According to the question
$4 a 3 + 9 8 4 = 1 3 b 7$
$a + 8 = b$
Then$b - a = 8$
According to the question  13b7 is divisible by 11
$(7 + 3) - (b + 1) = (9 - b)$
$(9 - b) = 0$
$b = 9$
$b = 9   and   a = 1$
Then $a+b=9+1=10$

In an examination, a student scores 4 marks for every correct answer and loses 1 mark for every wrong answer. If she attempts in all 50 questions and scores 120 marks, the number of questions she attempts correct is........

maths operations adding and subtracting numbers using place value addition & subtraction mental additions and subtractions

  1. 62

  2. 44

  3. 42

  4. 34

Show answer
Correct Option: D
Explanation:

Let student get x correct answer then 50-x student get wrong answer 
Then 4(x)+(50-x)(-1)=120
Or 4x-50+x=120
Or 5x=120+50=170
Or x=34

What is the value of $(\sqrt 7+\sqrt 5)(\sqrt 7-\sqrt 5)$?

maths operations adding and subtracting numbers using place value addition & subtraction mental additions and subtractions

  1. 1

  2. 2

  3. 5

  4. 3

Show answer
Correct Option: B
Explanation:

$(\sqrt 7+\sqrt 5)(\sqrt 7-\sqrt 5)$
$\Rightarrow \left(\sqrt {7}\right)^2-\left(\sqrt{5}\right)^2$
$\Rightarrow 7-5 =2$