Astudy of six hundred adults found that the number of hours they spend on social networking sites each week is normally distributed with a mean of 17 hours. the population standard deviation is 6 hours. what is the margin of error for a 95% confidence interval?

The margin of error for a 95% confidence interval is 0.48.

Step-by-step explanation:

Since we have given that

N = 600

Mean = 17 hours

Standard deviation = 6 hours

We need to find the margin of error for a 95% confidence interval.

Margin of error is given by

Here, n = 600,

In 95% confidence interval z = 1.96

So, Margin of error would be

Hence, the margin of error for a 95% confidence interval is 0.48.

step-by-step explanation:

the value of v.w= -12.

step-by-step explanation:

we are given three vector r,v and w as:

r = < 5, -5, -2> ; v = < 2, -8, -8> ; w = < -2, 6, -5>

we know that r,v and w could also be represented as:

r=5i-5j-2k

v=2i-8j-8k

and w= -2i+6j-5k

where i,j and k are the unit vectors of x,y and z-axis respectively.

also we know that it has the following property:

i.i=1 ; j.j=1; k.k=1

and i.=j.i=i.k=k.i=j.k=k.j=0

i.e. when we multiply two vectors or we find it's dot product we need to only multiply the components of x coordinates with each other; y with each other and z with each other.

hence, v.w= (2i-8j- -2i+6j-5k)

                  = 2×(-2)+(-8)×(6)+(-8)×(-5)

                  = -4-48+40

                  = -12

hence, v.w= -12