The general form for this is y^2 = 4ax where a = focus
the directrix is same distabce behind the vertex as focus is in font so focus a = 4
so we have y^2 = 16 x
or
x = (1/16) y^2
Its C
Using the mean concept, it is found that we will need 15 more points to bring up his average up to 90%.
The mean of a data-set is the <u>sum of all observations divided by the number of observations</u>.
In this problem:
- In the first 5 observations, total of 21 out of 25 points, hence the mean for these observations is
. - In the next n observations, mean of 1.
Hence, the mean is:

We want the mean to be of 0.9, thus:





3 more testes are need, each worth 5 points, hence, 15 more points are needed to bring up his average up to 90%.
A similar problem is given at brainly.com/question/25323941
8 White
6 Black
4 Blue
5 Brown
Total=8+6+4+5=23
1. White to brown = 8:5
2. Blue to non-blue =4:(23-4) = 4:19
3. Black to all = 6 : 23
4. Ratios equivalent to Q1, 8:5
Multiply ratio by integer factors:
2(8:5)=16:10
3(8:5)=24:15
4(8:5)=32:20
etc.