Martin earned the following scores on his last five tests. 98, 78, 84, 75, 91 what is the mean absolute deviation of his scores?

Step-by-step explanation:

find the average of his scores:

98 +78+84 +75 +91 = 426/5 = 85.2

now find the difference between the average and each test score:

98 - 85.2 = 12.8

85.2 -78 = 7.2

85.2 - 84 = 1.2

85.2 -75 = 10.2

91-85.2 = 5.8

 total those and divide by the number of tests

12.8 + 7.2 + 1.2 +10.2 +5.8 =37.2/5 = 7.44

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