There are two types of hot-water heaters: tank and inline. An experiment is to be conducted to determine whether the life of the hot-water heater is the same for both types of hot-water heaters. In previous studies, it was determined that family size (small, medium, large) is associated with life expectancy of the water heater, but house size (small, medium, large) is not associated with life expectancy of the water heater. How would blocking best be used?

blocking by family size

Step-by-step explanation:

got it right on the quiz :)

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

mk./km: lm

step-by-step explanation:

,mlmlm

; mk

lk