Answer:

Step-by-step explanation:
To find the rate of change of temperature with respect to distance at the point (3, 1) in the x-direction and the y-direction we need to find the Directional Derivative of T(x,y). The definition of the directional derivative is given by:

Where i and j are the rectangular components of a unit vector. In this case, the problem don't give us additional information, so let's asume:


So, we need to find the partial derivative with respect to x and y:
In order to do the things easier let's make the next substitution:

and express T(x,y) as:

The partial derivative with respect to x is:
Using the chain rule:

Hence:

Symplying the expression and replacing the value of u:

The partial derivative with respect to y is:
Using the chain rule:

Hence:

Symplying the expression and replacing the value of u:

Therefore:

Evaluating the point (3,1)

I’m can’t freakin stay up I need to sleep and I need to get 4 papers done for my portfolio I can’t help but I wish you luck
Answer:
0.0045 = 0.45% probability that less than two of them ended in a divorce
Step-by-step explanation:
For each marriage, there are only two possible outcomes. Either it ended in divorce, or it did not. The probability of a marriage ending in divorce is independent of any other marriage. This means that the binomial probability distribution is used to solve this question.
Binomial probability distribution
The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

In which
is the number of different combinations of x objects from a set of n elements, given by the following formula.

And p is the probability of X happening.
55% of marriages in the state of California end in divorce within the first 15 years.
This means that 
Suppose 10 marriages are randomly selected.
This means that 
What is the probability that less than two of them ended in a divorce?
This is

In which




0.0045 = 0.45% probability that less than two of them ended in a divorce
P(82 - q < x < 82 + q) = 0.44
P(x < 82 + q) - P(82 - q) = 0.44
P(z < (82 + q - 82)/7.4 - P(z < (82 - q - 82)/7.4) = 0.44
P(z < q/7.4) - P(z < -q/7.4) = 0.44
P(z < q/7.4) - (1 - P(z < q/7.4) = 0.44
P(z < q/7.4) - 1 + P(z < q/7.4) = 0.44
2P(z < q/7.4) - 1 = 0.44
2P(z < q/7.4) = 1.44
P(z < q/7.4) = 0.72
P(z < q/7.4) = P(z < 0.583)
q/7.4 = 0.583
q = 0.583 x 7.4 = 4.31