90+80+90+x=360
260+x=360
x=100

number of marks available = 140
percentage secured = 70%
therefore marks secured =

hope helpful~
First way is create an equation like this:
and calculating it.
Second way is to find 37% of each number and then add it

+

In both cases the result is 10.829
Answer:
f(-3) = -20
Step-by-step explanation:
We observe that the given x-values are 3 units apart, and that the x-value we're concerned with is also 3 units from the first of those given. So, a simple way to work this is to consider the sequence for x = 6, 3, 0, -3. The corresponding sequence of f(x) values is ...
34, 10, -8, ?
The first differences of these numbers are ...
10 -34 = -24
-8 -10 = -18
And the second difference is ...
-18 -(-24) = 6
For a quadratic function, second differences are constant. This means the next first-difference will be ...
? -(-8) = -18 +6
? = -12 -8 = -20
The value of the function at x=-3 is -20.
_____
The attachment shows using a graphing calculator to do a quadratic regression on the given points. The graph can then be used to find the point of interest. There are algebraic ways to do this, too, but they are somewhat more complicated than the 5 addition/subtraction operations we needed to find the solution. (Had the required x-value been different, we might have chosen a different approach.)
Answer:
V' = -0.11552 *V\\= -0.11552(1.8)\\ \\=-0.20794 million per year
Step-by-step explanation:
Given that oil is pumped continuously from a well at a rate proportional to the amount of oil left in the well. Initially there were 3 million barrels of oil in the well; six years later 1,500,000 barrels remain.
i.e. if V stands for volume of oil, then

To find A and k
V(0) = A = 3 million
Hence V = 
V(6) = 1.5
i.e. 

a) Using the above value of k , we have
million per year.