Statistics?

Question

4 students own the following # of calculators

Student A, B, C, D
# of calc 2, 1, 4, 3

-Find the mean and standard deviation:

-2 randon samples where drawn calculate mean and standard dev.

I really can't figure out part 2. And the problem doesn't say which random were taken it only says to use answer from part one for part 2

Answer 1

mean is the arithmatic sum divided by the number of samples:

(2+1+4+3)/4 = 10/4 = 2.5

the variance is found by the sum of (xi - xbar)^2 for all i and divided by (n-1) where i is an index variable i = 1, ..., n and n is the sample size. the standard deviation is the square root of the variance.

Variance = [(2-2.5)^2 + (1-2.5)^2 + (4-2.5)^2 + (3-2.5)^2]/(3) = 2.4166666

standard deviation is Sqrt(2.4166666) = 1.55

Answer 2

mean is the arithmatic sum divided by the number of samples:

(2+1+4+3)/4 = 10/4 = 2.5

the variance is found by the sum of (xi - xbar)^2 for all i and divided by (n-1) where i is an index variable i = 1, ..., n and n is the sample size. the standard deviation is the square root of the variance.

Variance = [(2-2.5)^2 + (1-2.5)^2 + (4-2.5)^2 + (3-2.5)^2]/(3) = 2.4166666

standard deviation is Sqrt(2.4166666) = 1.55


Can't answer the second part, what are the random samples that were drawn?

Answer 3

The mean is (2+1+4+3) / 4 = 2.5

I don't know this standard deviation

Mean means average

Answer 4

mean= (2+1+4+3)/4 == 2.5
sorry... don't know standard deviation

Answer 5

the mean=13/4
s.d. the square of the variance

Answer 6

Mean: (2+1+4+3)/4 = 2.5
StDev = sqrt[(2-2.5)^2 + (1-2.5)^2 + (4-2.5)^2 + (3-2.5)^2] =
sqrt[0.5*0.5 + 1.5*1.5 + 1.5*1.5 + 0.5*0.5] = sqrt(5)