Combined mean and standard deviation -illustration, Mathematics

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 1st sample

Assume n2 be the size of the 2nd sample

Assume s1 be the standard deviation of the 1st sample

Assume s2 be the standard deviation of the 2nd sample

∴ Combine mean = (n1x1 + n2x2)/(n1n2)

 

                        2267_Combined mean.png

 

 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

Posted Date: 2/18/2013 1:10:20 AM | Location : United States







Related Discussions:- Combined mean and standard deviation -illustration, Assignment Help, Ask Question on Combined mean and standard deviation -illustration, Get Answer, Expert's Help, Combined mean and standard deviation -illustration Discussions

Write discussion on Combined mean and standard deviation -illustration
Your posts are moderated
Related Questions
We have independent observations Xi, for i = 1, . . . , n, from a mixture of m Poisson distributions with component probabilities d c and rates l c, for c = 1, . . . ,m. We decid

state tha different types of models used in operations research.

how much congruent sides does a trapezoid have

#stioquen..Store A is advertising a sale that will reduce prices on all merchandise by 15%. Store B is advertising a sale that will reduce prices on all merchandise by one over fiv

how do you find the length of a parallel line connecting two external circles of different sizes from the outside, given the value of both radius and one parallel line.

Reduction -when the original amount and the balance or remainder are known, to find the part that has been given away. (e.g., there were 15 toffees in a container, and there are

Al is painting a right cylinder storage tank. In sequence to purchase the correct amount of paint he requires to know the total surface area to be painted. Which formula will he us


Graphical Method While drawing the graph on a natural scale, the independent variables are marked along the horizontal line and corresponding dependen

Cycloid The parametric curve that is without the limits is known as a cycloid.  In its general form the cycloid is, X = r (θ - sin θ) Y = r (1- cos θ)  The cycloid pre