=4n - 1
Since the sequence is add 4 and 3-4 = -1
20 x 4n = 80-1 = 79
Answer:
a)
.
b) 
Step-by-step explanation:
Given a function
, this function has the following gradient:
.
(a) find the gradient of f
We have that
. So


.
.

(b) find the directional derivative of f at (2, 4, 0) in the direction of v = i + 3j − k.
The directional derivate is the scalar product between the gradient at (2,4,0) and the unit vector of v.
We have that:

.

The vector is 
To use v as an unitary vector, we divide each component of v by the norm of v.

So

Now, we can calculate the scalar product that is the directional derivative.

Answer:
B. People who were promised free samples of Penelope‘s puffy popcorn for completing the survey
Step-by-step explanation:
This would show likely bias in the result of the survey
I would recommend calculatorsoup.com for the fractions part.
Answer:
The first choice, students tend to have less siblings than teachers
Step-by-step explanation:
If you look at the dot plots you notice that the teachers have more numbers than the students do and that the students have less sibling. It is not answer 2 because the students have less sibling, it is not answer 3 b/c they do not have the same range, and it is not number 4 because they do not look the same or have the same shape.