If ∑(xᵢ−a)=n and ∑(xᵢ−a)²=na, then... | Statistics | JEE Main 2020

Competishun Header

JEE MAIN 2020

06-09-2020_S1

Question

If $\sum_{i=1}^n\left(x_i-a\right)=n$ and $\sum_{i=1}^n\left(x_i-a\right)^2=n a,(n, a>1)$ then the standard deviation of $n$ observations $x_1, x_2, \ldots, x_n$ is :

Select the correct option:

A

$a-1$

B

$n \sqrt{a-1}$

C

$\sqrt{\mathrm{n}(\mathrm{a}-1)}$

D

$\sqrt{a-1}$

✓ Correct! Well done.

✗ Incorrect. Try again or view the solution.

Solution

Question Tags

JEE Main

Mathematics

Easy

Start Preparing for JEE with Competishun

Video Solution

BY competishun

Watch Solution

YouTube

Filters 0

Showing 18 questions

A wedge $Y$ with mass of 10 kg and all frictionless surfaces and the inclined surface making $37^{\circ}$ with horizontal....

JEE MainPhysicsHard

View Solution→

Three masses $m_1=4 \mathrm{~kg}, m_2=4 \mathrm{~kg}$ and $m_3=6 \mathrm{~kg}$ are suspended from a fixed smooth frictionless pulley as shown in...

JEE MainPhysicsMedium

View Solution→

When one moves from a point 16 km below the earth's surface to a point 16 km above the earth's...

JEE MainPhysicsMedium

View Solution→

$\mathrm{L}, \mathrm{C}$ and R represents physical quantities inductance, capacitance and resistance respectively. The dimensional formula $\mathrm{ML}^2 \mathrm{~T}^{-4} \mathrm{~A}^{-2}$ corresponds to...

JEE MainPhysicsHard

View Solution→

In a Vernier calipers, when both jaws touch each other, zero of the Vernier scale is shifted to the right...

JEE MainPhysicsEasy

View Solution→

A body of mass 2 kg begins to move under the influence of time dependent force $...

JEE MainPhysicsMedium

View Solution→

QJEE Mains 20262026

A salt with few drops of conc. HCl gives apple green colour in flame test. The group precipitate of the...

JEE MainChemistryMedium

View Solution→

QJEE Mains 20262026

Consider the three aromatic molecules (P, Q and R) whose structures have been given below :

JEE MainChemistryMedium

View Solution→

QJEE Mains 20262026

Match the following

JEE MainChemistryEasy

View Solution→

The velocity of a particle executing simple harmonic motion along $x$-axis is described as $v^2=50-x^2$, where x represents displacement. If...

JEE MainPhysicsEasy

View Solution→

The surface tension of a soap solution is $3.5 \times 10^{-2} \mathrm{~N} / \mathrm{m}$. The work required to increase the...

JEE MainPhysicsMedium

View Solution→

A 1 kg block subjected to two simultaneous forces $(2 \hat{\mathrm{i}}+3 \hat{\mathrm{j}}+4 \hat{\mathrm{k}}) \mathrm{N}$ and $(3 \hat{i}-\hat{j}-2 \hat{k}) \mathrm{N}$ is...

JEE MainPhysicsEasy

View Solution→

An unpolarized light is incident on the plane interface of air-dielectric medium shown in figure. If the incident angle is...

JEE MainPhysicsHard

View Solution→

The voltage and the current between A and B points shown in the circuit are _____.

JEE MainPhysicsMedium

View Solution→

QJEE Main 20262026

For the given molecule, "x", the preferred site for the attack of the electrophile is :

JEE MainChemistryEasy

View Solution→

QJEE Mains 20262026

In IUPAC nomenclature, the correct order of decreasing priority of functional group is:

JEE MainChemistryEasy

View Solution→

QJEE Main 20262026

Given below are two statements:
Statement (I) : Benzyl chloride reacts faster in $\mathrm{S}_{\mathrm{N}} 1$ mechanism than ethyl chloride.
...

JEE MainPhysicsEasy

View Solution→

Consider a circuit consisting of a capacitor $(20 \mu \mathrm{~F})$, resistor $(100 \Omega)$ and two identical diodes as shown in...

JEE MainPhysicsMedium

View Solution→