The answer is number 2) Increase the resistance of the concrete to freeze-thaw damage.
Answer with Explanation:
Part a)
The volume of water in the tank as a function of time is plotted in the below attached figure.
The vertical intercept of the graph is 46.
Part b)
The vertical intercept represents the volume of water that is initially present in the tank before draining begins.
Part c)
To find the time required to completely drain the tank we calculate the volume of the water in the tank to zero.

Part d)
The horizontal intercept represents the time it takes to empty the tank which as calculated above is 13.143 minutes.
This is a very very difficult one for me, let me get back to you with the proper answer.
Answer:
The answer is "
and 157.5 MPa".
Explanation:
In point A:
The strength of its products with both the grain dimension is linked to this problem. This formula also for grain diameter of 310 MPA is represented as its low yield point

Here y is MPa is low yield point, x is mm grain size, and k becomes proportionality constant.
Replacing the equation for each condition:

People can get yo = 275 MPa with both equations and k= 15.5 Mpa
.
To substitute the answer,

In point b:
The equation is 
equation is:

by putting the above value in the formula we get the
value that is= 157.5 MPa
Answer: find the answer in the explanation.
Explanation:
Some of the methods of science are hypothesis, observations and experiments.
Scientific research and findings cut across many areas and field of life. Field like engineering, astronomy and medicine e.t.c
Using models in research is another great method in which researchers and scientists can master a process of a system and predict how it works.
Wilbur and Orville Wright wouldn't have died if the first airplane built by these two wonderful brothers was first researched by using models and simulations before embarking on a test.
Modelling in science involves calculations by using many mathematical methods and equations and also by using many laws of Physics. In this present age, many of these are computerised.
In space science, it will save lives, time and money to first model and simulate if any new thing is discovered in astronomy rather than people going to the space by risking their lives.
Also in medicine, drugs and many medical equipment cannot be tested by using people. This may lead to chaos and loss of lives.
So research using models in astronomy, medicine, engineering and many aspects of science and technology can indeed save lives.