Answer:
The variance for the number of correct answers is 2.8 questions
Step-by-step explanation:
The number of correct answers follows binomial distribution, in which we have:
- n identical and independents events: the 15 questions
- two possibles results that we call success and fail: The answer is correct and the answer is incorrect
- probability p of success and 1-p of fail. Probability 1/4 of get the answer correct and probability of 3/4 of get the answer incorrect. This probabilities are calculated on that way because every question have 4 possible answers and one of which is correct.
So, the variance for a variable x that follows a Binomial distributions is:
V(x)=n*p*(1-p)
Then, the variance for the number of correct answers is:
V(x)=15*(1/4)*(3/4) = 2.8125 ≈ 2.8
Because n is equal to 15, p is equal to 1/4 and (1-p) is equal to 3/4.
Answer:
x = -2, 3, -4.
Step-by-step explanation:
x^3 - 10x = -3x2 + 24 = 0
x^3 + 3x^2 - 10x - 24 = 0
The last term is 24 and the coefficient of x^3 is 1 so +/- 1, +-2, +/- 3 and +/- 4 could be among the roots ( by The Rational Root Theorem).
Let x = 1
f(x) = 1^3 +3(1)^2 - 10 - 24 = -30 so it's no t .
f(-1) = -1 + 3 + 10 - 24 = -12 so it's not -1.
Let x = 2:
f(2) = 2^3 +3*4 - 20 - 24 = -32 so its not 2
f(-2) = -8 + 12 + 20 - 24 = 0 so x = -2 is a root
and therefore x+ 2 is a factor and we divide:
x + 2 ) x^3 + 3x^2 - 10x - 24 ( x^2 + x - 12 <------ The quotient
x^3 + 2x^2
x^2 - 10x
x^2 + 2x
-12x - 24
-12x - 24
..............
Now x^2 + x - 12 = (x - 3)(x + 4)
So (x + 2)(x - 3)(x + 4) = 0
This gives
x = -2, 3, -4.
Basically just do the problem backwards.
72÷9=8
72÷8=9
Answer:
I think it may be H. but let me know if i am wrong. if i am right plz mark brainliest
Step-by-step explanation:
27 divided by 3 is 9, 27/3=9 because 27/3 is the same exact thing as 27 divided by 3. So the answer has to be 9
I think it’s D because the only thing that happen was that they rotated so I think it’s D but if it’s wrong sorry
