Answer

Verified

381k+ 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

what is the correct chronological order of the following class 10 social science CBSE

Which of the following was not the actual cause for class 10 social science CBSE

Which of the following statements is not correct A class 10 social science CBSE

Which of the following leaders was not present in the class 10 social science CBSE

Garampani Sanctuary is located at A Diphu Assam B Gangtok class 10 social science CBSE

Which one of the following places is not covered by class 10 social science CBSE

Trending doubts

How do you graph the function fx 4x class 9 maths CBSE

Which are the Top 10 Largest Countries of the World?

The Equation xxx + 2 is Satisfied when x is Equal to Class 10 Maths

Difference Between Plant Cell and Animal Cell

Difference between Prokaryotic cell and Eukaryotic class 11 biology CBSE

1 ton equals to A 100 kg B 1000 kg C 10 kg D 10000 class 11 physics CBSE

In Indian rupees 1 trillion is equal to how many c class 8 maths CBSE

The largest tea producing country in the world is A class 10 social science CBSE

One Metric ton is equal to kg A 10000 B 1000 C 100 class 11 physics CBSE