Tag: maths

Questions Related to maths

The greatest of the number 
$1,2^{1/2},3^{1/3},4^{1/4},5^{1/5}, 6^{1/6}, and \ 7^{1/7}$ is

  1. $2^1/2$

  2. $3^1/3$

  3. $7^1/7$

  4. $4^1/4$


Correct Option: B

${ 5 }^{ n }\left( n\in N \right) $ ends with ......

  1. 4

  2. 0

  3. 5

  4. 2


Correct Option: C
Explanation:
 $n$  $1$  $2$  $3$  $4$  $5$
 ${5}^{n}$  $5$  $25$  $125$  $625$  $3125$
 Ending number  $5$  $5$  $5$  $5$  $5$

Thus, the number ends with $5$ for $n\in N$ and $n$ is odd or even.

Find the value of $\displaystyle\frac{5^0+5^{-1}}{5^0-5^{-1}}-\left(\frac{8}{27}\right)^{\displaystyle\frac{1}{3}}-\left(\frac{36}{25}\right)^{-\displaystyle\frac{1}{3}}$

  1. 0

  2. $\displaystyle\frac{1}{2}$

  3. 1

  4. 2


Correct Option: A
Explanation:

$\displaystyle\frac{\displaystyle1+\frac{1}{5}}{\displaystyle1-\frac{1}{5}}-\left[\left(\frac{2}{3}\right)^3\right]^{\displaystyle\frac{1}{3}}-\left[\left(\frac{6}{5}\right)^2\right]^{\displaystyle-\frac{1}{2}}=\frac{\displaystyle\frac{6}{5}}{\displaystyle\frac{4}{5}}-\left(\frac{2}{3}\right)^1-\left(\frac{6}{5}\right)^{-1}=\frac{6}{4}-\frac{2}{3}-\frac{5}{6}=\frac{18-8-10}{12}=0$

The approximate value of ${ \left{ { { \left( 3.92 \right)  }^{ 2 }\quad +3\left( 2.1 \right)  }^{ 4 } \right}  }^{ { 1 }/{ 6 } }$

  1. $2.0466$

  2. $2.755$

  3. $2.345$

  4. $0.242718$


Correct Option: A
Explanation:

${(3.92^2+3(2.1^4)}^\dfrac{1}{6}$

 
$=(15.3664+3\times19.4481)^\dfrac{1}{6}$


$=(15.3664+58.3443)^\dfrac{1}{6}$

$=(73.7107)^\dfrac{1}{6}$

$=2.0476$

If ${2}^{1998}-{2}^{1997}-{2}^{1996}+{2}^{1995}={K.2}^{1995}$, then the value of $K$ is 

  1. 3

  2. 2

  3. -2

  4. -3


Correct Option: A
Explanation:
$2^{1998}-2^{1997}-2^{1996}+2^{1995}=k. 2^{1995}$
$2^{1995}(2^3-2^2-2^1+1)=k. 2^{1995}$
$(2^3-2^2-2^1+1)=k$
$(8-4-2+1)=k$
$k=3$

If $\displaystyle { 2 }^{ n }-{ 2 }^{ n-1 }=4$, then the value of $\displaystyle { n }^{ n }$ will be -

  1. 1

  2. $\displaystyle \frac { 3 }{ 2 } $

  3. 2

  4. 27


Correct Option: D
Explanation:

$\displaystyle { 2 }^{ n }-{ 2 }^{ n-1 }=4$
$\displaystyle \therefore \quad { 2 }^{ n-1 }\left( 2-1 \right) =4$
$\displaystyle \therefore \quad { 2 }^{ n-1 }={ 2 }^{ 2 }$
$\displaystyle \therefore \quad n-1=2$
$\displaystyle \therefore \quad n=3$
$\displaystyle \therefore \quad { n }^{ n }={ 3 }^{ 3 }=27$

$\displaystyle \frac { { \left( 3.63 \right)  }^{ 2 }-{ \left( 2.37 \right)  }^{ 2 } }{ 3.63+2.37 } $ is simplified to -

  1. 6

  2. 1.36

  3. 2.26

  4. 1.26


Correct Option: D
Explanation:

$\displaystyle \frac { { \left( 3.63 \right)  }^{ 2 }-{ \left( 2.37 \right)  }^{ 2 } }{ 3.63+2.37 } $
$\displaystyle =\frac { \left( 3.63+2.37 \right) \left( 3.63-2.37 \right)  }{ 3.63+2.37 } $
$\displaystyle =3.63-2.37$
$\displaystyle =1.26$

Value of $\displaystyle\frac{2^{100}}{2}$ is

  1. $1$

  2. $\displaystyle 50^{100}$

  3. $\displaystyle 2^{50}$

  4. $\displaystyle 2^{99}$


Correct Option: D
Explanation:

$\displaystyle 2^{100}\div 2^1=2^{100-1}=2^{99}$

Simplest form of the Expression $\displaystyle { \left( { x }^{ 6 }.{ y }^{ { -5 }/{ 4 } } \right)  }^{ { -4 }/{ 3 } }$ will be-

  1. $\displaystyle { x }^{ -24 }y$

  2. $\displaystyle { x }^{ -8 }{ y }^{ { 5 }/{ 3 } }$

  3. $\displaystyle { x }^{ 8 }{ y }^{ { -5 }/{ 3 } }$

  4. $\displaystyle { x }^{ -8 }{ y }^{ { -5 }/{ 3 } }$


Correct Option: B
Explanation:

$\displaystyle { \left( { x }^{ 6 }.{ y }^{ { -5 }/{ 4 } } \right)  }^{ { -4 }/{ 3 } }$
$\displaystyle ={ x }^{ -6\times { 4 }/{ 3 } }{ y }^{ \dfrac { -5 }{ 4 } \times -\dfrac { 4 }{ 3 }  }$
$\displaystyle ={ x }^{ -8 }{ y }^{ { 5 }/{ 3 } }$

A man eats $200:g$ of rice a day and he has enough rice to last him for $35$ days. How long would the stock of rice last him if he were to eat $250:g$ rice a day.

  1. $\;42$

  2. $\;21$

  3. $\;28$

  4. $\;49$


Correct Option: C
Explanation:

Man eat $ 200$ g rice in a day then he  has $35\times 200=7000  g $ rice for  $35$  days
But if he eat  $250$  g rice in a day
Then $7000$  g rice is enough for $\dfrac{7000}{250}=28  \ days$