Write a recursive definition for the sequence 21,16,11,6
1 answer:
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Given:
The focus of the parabola is at (6,-4).
Directrix at y=-7.
To find:
The equation of the parabola.
Solution:
The general equation of a parabola is:
...(i)
Where, (h,k) is vertex, (h,k+p) is the focus and y=k-p is the directrix.
The focus of the parabola is at (6,-4).
On comparing both sides, we get
...(ii)
Directrix at y=-7. So,
...(iii)
Adding (ii) and (iii), we get
Putting in (ii), we get
Putting in (i), we get
Therefore, the equation of the parabola is .
Answer: About 191 students scored between a 60 and an 80.
Step-by-step explanation:
Given : A set of 200 test scores are normally distributed with a mean of 70 and a standard deviation of 5.
i.e. and
let x be the random variable that denotes the test scores.
Then, the probability that the students scored between a 60 and an 80 :
The number of students scored between a 60 and an 80 = 0.9544 x 200
= 190.88 ≈ 191
Hence , about 191 students scored between a 60 and an 80.