Tag: maths

Questions Related to maths

Reciprocal of $\displaystyle \frac{7}{5}$

  1. $\displaystyle 1\frac{2}{5}$

  2. $\displaystyle \frac{5}{7}$

  3. $\displaystyle 5\frac{2}{3}$

  4. $\displaystyle \frac{12}{5}$


Correct Option: B
Explanation:
In the reciprocal, numerator and denominator interchanges
So, the reciprocal of $\dfrac{7}{5}$ is $\dfrac{5}{7}$.
Hence, the answer is $\dfrac{5}{7}$.

$\displaystyle \frac{1}{9}$ of ___ $= 5$

  1. $5$

  2. $9$

  3. $14$

  4. $45$


Correct Option: D
Explanation:

$\dfrac{1}{9}$ of $45=5$ because $45$ is divided by $9$ in $5$ times.

Hence, the answer is $45$.

Find the product:

$\displaystyle 1\frac{1}{3}\times 3\frac{1}{4}\times \frac{7}{8}$

  1. $\displaystyle 3\frac{18}{24}$

  2. $\displaystyle 2\frac{19}{24}$

  3. $\displaystyle 3\frac{19}{24}$

  4. $\displaystyle 2\frac{18}{24}$


Correct Option: C
Explanation:

Let's first convert the mixed fraction into simple fraction $\dfrac{4}{3},$ $\dfrac{13}{4},$ $\dfrac{7}{8}$ .

The product is 
$\dfrac{4}{3} \times \dfrac{13}{4}\times \dfrac{7}{8}=\dfrac{91}{24}$
This can also be written as $3\dfrac{19}{24}$.

If $\displaystyle 40-\frac{1}{5}\times $ ____ $= 0$, then the missing value is 

  1. $0$

  2. $\displaystyle \frac{1}{5} $

  3. $\displaystyle \frac{199}{5} $

  4. $200$


Correct Option: D
Explanation:
Let missing value is $x$

$40$ $-\dfrac{1}{5}\times x=0$

$40$ $=\dfrac{1}{5}\times x$

$x=200$

Hence, the answer is $200$.

If the reciprocal of $y - 1$ is $y + 1$, then $y$ equals

  1. $-1$

  2. $+1$

  3. $0$

  4. $\pm$ 1

  5. none of these


Correct Option: E
Explanation:

Reciprocal of $y-1$ is $\dfrac{1}{y-1} = y+1$, so we get ${y}^{2}-1=1$
Which implies $y = \pm \sqrt2$
So, the correct option is $E$.

Without using truth , whether
$\left[ {p\Delta \left( { \sim q\Delta r} \right)} \right]V\left[ { \sim r\Delta  \sim q\Delta p} \right] \equiv p$

  1. True

  2. False


Correct Option: B

Solve it:-
$\left( {p \to q} \right) \to [\left( { \sim p \to q} \right) \to q]$

  1. Tautology

  2. Contradiction

  3. Contingent

  4. Not statement


Correct Option: A
Explanation:
$Y=\left( p\longrightarrow q \right) \longrightarrow \left[ \left( \sim p\longrightarrow q \right) \longrightarrow q \right]$
Method : TRUTH TABLE [  ALWAYS PREFERABLE]

 $p$  $q$  $p\longrightarrow q$  $\left( \sim p\longrightarrow q \right) $  $\left[ \left( \sim p\longrightarrow q \right) \longrightarrow q \right]$  $Y$
 $1$  $0$  $0$  $1$  $1$ $1$ 
 $1$  $1$  $1$  $1$  $1$  $1$
 $0$  $0$  $1$  $0$  $1$  $1$
 $0$  $1$  $1$  $1$  $1$  $1$
As the result is always TRUE $\left(i.e. 1\right)$;
$\left( p\longrightarrow q \right)\longrightarrow \left[ \left( \sim p\longrightarrow q \right) \longrightarrow q \right]$ is Tautology.

A. Tautology



















Which of the following is true

  1. $a _{r}=a _{n-r}$

  2. $a _{2r}=a _{n-r}$

  3. $a _{r}=a _{2n-r}$

  4. $None\ of\ these$


Correct Option: A

Let $p$ and $q$ be two propositions given by
$p$ : The sky is blue.
$q$ : The milk is white.
Then $p\wedge q$ will be

  1. The sky if blue or milk is white

  2. The sky is blue and milk is white

  3. The sky is white and milk is blue

  4. If the sky is blue then milk is white


Correct Option: B
Explanation:

$p \wedge q$ means statement p and q
=> The sky is blue and  milk is white.

Let $p$ and $q$ be two propositions. Then the contrapositive the implication $p\rightarrow q$

  1. $\sim q\rightarrow \sim p$

  2. $\sim p\rightarrow \sim q$

  3. $q\rightarrow p$

  4. $p\leftrightarrow q$


Correct Option: A
Explanation:

the contrapositive of $p\to q$ is $\sim q\to \sim p$