Combined mean and standard deviation -illustration, Mathematics

Assignment Help:

Combined mean

Assume m be the combined mean

Assume x₁ be the mean of first sample

Assume x₂ be the mean of the second sample

Assume n₁ be the size of the 1^st sample

Assume n₂ be the size of the 2^nd sample

Assume s₁ be the standard deviation of the 1^st sample

Assume s₂ be the standard deviation of the 2^nd sample

∴ Combine mean = (n₁x₁ + n₂x₂)/(n₁n₂)

Illustration

A sample of 40 electric batteries described a mean life span of 600 hours along with a standard deviation of 20 hours.

Other sample of 50 electric batteries described a mean lifespan of 520 hours along with a standard deviation of 30 hours.

If these two samples were combined and utilized in a given project simultaneously, find out the combined new mean for the larger sample and hence find out the combined or pulled standard deviation.

Size x s

40(n₁) 600 hours (x₁) hours (s₁)

50 (n₁) 520 hours (x₂) 30 hours (s₂)

Combined mean = (40(600) + 50 (520))/(40 + 50)

=50,000/90

= 555.56

Combined standard deviation

825_Combined mean 1.png

Related Discussions:- Combined mean and standard deviation -illustration

iq type question, 1 1 1 1 1 2 1 2 ? and 40/2=? ...

1 1 1 1 1 2 1 2 ? and 40/2=? 2/40=?

Numerical method, find the newton raphson iterative formula for a reciproca...

find the newton raphson iterative formula for a reciprocal of a number N and hence find the value of 1/23

Pre calc, - Find the total surface area of a frustum of a cone. (Include to...

- Find the total surface area of a frustum of a cone. (Include top and bottom). The equation that I have for volume is v=1/3 pi x h(r^2+rR+R^2) -the equation that I have found fo

Greatest common factor, Greatest Common Factor The primary method for f...

Greatest Common Factor The primary method for factoring polynomials will be factoring the greatest common factor. While factoring in general it will also be the first thing

Calculus, I need an explanation of "the integral, from b to a, of the deriv...

I need an explanation of "the integral, from b to a, of the derivative of f (x). and, the integral from a to b. of the derivative of f(t) dt.

Unitarymethod, who discovered and when

who discovered and when

Quadratic polynomials, example with solution of quadratic polynomial

example with solution of quadratic polynomial

Cylinder, #question Show that the enveloping cylinder of the conicoid ax 2 ...

#question Show that the enveloping cylinder of the conicoid ax 2 + by 2 + cz 2 = 1 with generators perpendicular to the z-axis meets the plane z = 0 in parabolas

Find out general formula for tangent vector and unit vector, Find out the g...

Find out the general formula for the tangent vector and unit tangent vector to the curve specified by r → (t) = t 2 i → + 2 sin t j → + 2 cos t k → . Solution First,

Projections - vector, Projections The good way to understand projection...

Projections The good way to understand projections is to see a couple of diagrams. Thus, given two vectors a → and b → we want to find out the projection of b → onto a → . T

Write Your Message!

Name

Email id

Message

Verfication Code

User Account

All Pages