Tag: representation of rational numbers on number line

Questions Related to representation of rational numbers on number line

A rational number lie between $\displaystyle\frac{1}{4}$ and $\displaystyle\frac{1}{3}$ is _________.

  1. $\displaystyle\frac{7}{24}$

  2. $0.29$

  3. $\displaystyle\frac{13}{48}$

  4. All of these


Correct Option: D
Explanation:

We know $\dfrac{1}{4} = 0.25$

and $\dfrac{1}{3}=0.3333333$

Option A: $\dfrac{7}{24}$
$=0.291666$
lies between the given numbers

Option B: $ 0.29$
lies between the given numbers

Option C: $\dfrac{13}{48}$
$=0.27083333$
lies between the given numbers.

All the options are correct.

Number of rational numbers between $15$ and $18$ is:

  1. infinite

  2. finite

  3. zero

  4. one


Correct Option: A
Explanation:

Between any two rational numbers we can find infinitely many rational numbers. 

Thus, number of rational numbers between $15$ and $18$ is infinite.
Hence, the answer is infinite.

A rational number -2/3 ______ .

  1. Lies to the left side of 0 on the number line.

  2. Lies to the right side of 0 on the number line.

  3. It is not possible to represent on the number line.

  4. Cannot be determined on which side the number lies.


Correct Option: A
Explanation:

rational number always lies on the line.

 this rational number is $\dfrac{-2}{3}$ which is negative  hence it is always lies to left side of $0$ on the number line.
hence option $A$ is correct.

Among the following 
$-\frac{3}{2},-1,3,0,\frac{1}{2}$
find the rational numbers less than $2.$
  1. $0$

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

  3. $-1$

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


Correct Option: A,B,C,D
Explanation:

$\dfrac{-3}{2},-1,3,0,\dfrac{1}{2}$


$-1.5,-1,3,0,0.5$


$\implies $ Among five rational numbers $-1.5,-1,0,0.5$ are lesser than $2$ expect $3$.


All options are correct.

There are infinite rational numbers between $2.5$ and $3$.

  1. True

  2. False


Correct Option: A
Explanation:

There are infinite rational numbers between any two rational numbers 

Choose the rational number which does not lie between rational numbers $-\dfrac{2}{5}$ and $-\dfrac{1}{5}$.

  1. $-\dfrac{1}{4}$

  2. $-\dfrac{3}{10}$

  3. $\dfrac{3}{10}$

  4. $-\dfrac{7}{20}$


Correct Option: C
Explanation:

For a rational number to lie between $\dfrac{-2}{5}$ and $\dfrac{-1}{5}$,it should be less than $\dfrac{-1}{5}$ and greater than $\dfrac{-2}{5}$.
Now,$\dfrac{3}{10}$ is not less than $\dfrac{-1}{5}$.
So,$\dfrac{3}{10}$ does not lie between $\dfrac{-1}{5}$ and $\dfrac{-2}{5}$.

Choose the rational number which does not lie between rational numbers $\dfrac{3}{5}$ and $\dfrac{2}{3}$.

  1. $\dfrac{46}{75}$

  2. $\dfrac{47}{75}$

  3. $\dfrac{49}{75}$

  4. $\dfrac{50}{75}$


Correct Option: D
Explanation:

All the options have denominator $75$. Hence, let us convert into equivalent fractions having denominator $75$. 
$\dfrac{3}{5} $ $=\dfrac{3\times 15}{5\times 15} $ $=\dfrac{45}{75}$

$\dfrac{2}{3}$ $=\dfrac{2\times 25}{3\times 25}$ $=\dfrac{50}{75}$

Hence, $\dfrac{50}{75}$ does not lie between the given numbers.

Rationalising the denominator of $\dfrac {5}{\sqrt 3-\sqrt 5}$ is -

  1. $(\frac {5}{2}(\sqrt 3+\sqrt 5)$

  2. $(-\frac {5}{2}(\sqrt 3+\sqrt 5)$

  3. $(\frac {5}{2}(\sqrt 3-\sqrt 5)$

  4. $(-\frac {5}{2}(\sqrt 3-\sqrt 5)$


Correct Option: B
Explanation:

here, $\dfrac {5}{\sqrt 3-\sqrt 5}$

$=\dfrac {5}{\sqrt 3-\sqrt 5}\times \dfrac {\sqrt 3+\sqrt 5}{\sqrt 3+\sqrt 5}$

$=\dfrac {5(\sqrt 3+\sqrt 5)}{3-5}$


$=-\dfrac {5}{2}(\sqrt 3+\sqrt 5)$

The rational number lies between $\dfrac{3}{7}$ and $\dfrac{2}{3}$ is

  1. $\dfrac{2}{5}$

  2. $\dfrac{4}{7}$

  3. $\dfrac{3}{7}$

  4. $\dfrac{3}{3}$


Correct Option: A

A train of length 180 m crosses a man standing on a platform in 12 seconds and cross another train coming from opposite direction in 12 sec. If the second train running at 2/3 rd speed of the firstthen find the length of the second train?

  1. 56

  2. 120

  3. 20

  4. 44


Correct Option: B
Explanation:

Length of the first train$=180m$


 Time taken by  the train to cross the man standing on the platform$=12s$


Speed of the first train$=\dfrac{180}{12}$

                                      $=15m/s$

Speed of the second train$=\dfrac{2}{3}\times15$

                                            $=10m/s$

Relative speed$=15+10$

                          $=25m/s$
 
Let the length of the train be $y$ metres.

$Distance =Speed\times time$

$y+180=25\times12$

$y+180=300$

$y=300-180$
$y=120$
So, the length of the second train$=120m$