Answer

Verified

353.7k+ views

**Hint:**In this problem, we are given that the mean of 5 numbers is 20, if one number is excluded their mean is 15 we have to find the excluded number. We know that the formula for mean is the sum of the numbers divided by the total number. we can first find the sum of the given total number 5 and mean value 20, we can then find the sum whose mean value is 15 and if one number is excluded we will have total number 4. We can then subtract both the sums to get the excluded number.

**Complete step by step answer:**

Here we are given that the mean of 5 numbers is 20, if one number is excluded their mean is 15 we have to find the excluded number.

We know that the formula to find the mean value is,

\[\Rightarrow \dfrac{Sum}{Total}=Mean\]

We can now substitute the given values, where the total number is 5 and the mean value is 20.

\[\begin{align}

& \Rightarrow \dfrac{Sum}{5}=20 \\

& \Rightarrow Sum=100......\left( 1 \right) \\

\end{align}\]

We can now find the sum, whose mean value is 15 and the total value is 4 (where 1 number is excluded from the total number 5), we get

\[\begin{align}

& \Rightarrow \dfrac{Sum}{4}=15 \\

& \Rightarrow Sum=60......\left( 2 \right) \\

\end{align}\]

We can now subtract (1) and (2), we get

\[\Rightarrow 100-60=40\]

The excluded number is 40.

**So, the correct answer is “Option B”.**

**Note:**We should always remember that the formula for mean is the sum of the numbers divided by the total number. We should also understand that if one number is excluded means, from the total of 5 numbers one id excluded and we will get the total as 4.

Recently Updated Pages

List the name of the women who had achieved literacy class 8 social science CBSE

Select the antonym for the word EXTREME from the below class 8 english CBSE

Which of the following was not an important crop of class 8 social science CBSE

Which temples were built by the Nayaks of Madurai This class 8 social science CBSE

Choose the word which can be substituted for the given class 8 english CBSE

Choose the correct option whose meaning is given below class 8 english CBSE

Trending doubts

Differentiate between homogeneous and heterogeneous class 12 chemistry CBSE

Fill the blanks with the suitable prepositions 1 The class 9 english CBSE

Which are the Top 10 Largest Countries of the World?

Difference between Prokaryotic cell and Eukaryotic class 11 biology CBSE

Give 10 examples for herbs , shrubs , climbers , creepers

Write a letter to the principal requesting him to grant class 10 english CBSE

Change the following sentences into negative and interrogative class 10 english CBSE

Difference Between Plant Cell and Animal Cell

10 examples of law on inertia in our daily life