Answer: We reject the null hypothesis, and we use Normal distribution for the test.
Step-by-step explanation:
Since we have given that
We claim that
Null hypothesis : 
Alternate hypothesis : 
There is 5% level of significance.

So, the test statistic would be

Since alternate hypothesis is left tailed test.
So, p-value = P(z≤-2.31)=0.0401
And the P-value =0.0401 is less than the given level of significance i.e. 5% 0.05.
So, we reject the null hypothesis, and we use Normal distribution for the test.
The point of elimination is to have one variable so example
3x + 2y = 4
7X + 3y = 5
1) Try to find a way to have one variable
7(3x + 2y = 4) ----> 21x + 14y = 28
-3(7x+ 3y = 5) -----> -21x -9y = -15
2) add
0 + 5y = 13
3) solve for the last variable
5y = 13
y = 13/5 = 2 3/5 = 2.8
4) Subsitute the variable to get the other one
3x + 2(2.8) = 4
3x + 5.6 = 4
3x = -1.6
x = 0.533333333 (continue)
The intersection would be 0.53 with a line above the 3 and 2.8. (0.5333 , 2.8)
Hope you understand!!
To find the volume, you do area multiplied by thickness( or height)
In this example, you do (1/2*9*6)*10 which is 270
hope I helped ;)
The answer to you question is B for number 1 and for 2 it is C. Hope this helps