Answer:
Step-by-step explanation:
Let many universities and colleges have conducted supplemental instruction(SI) programs. In that a student facilitator he meets the students group regularly who are enrolled in the course to promote discussion of course material and enhance subject mastery.
Here the students in a large statistics group are classified into two groups:
1). Control group: This group will not participate in SI and
2). Treatment group: This group will participate in SI.
a)Suppose they are samples from an existing population, Then it would be the population of students who are taking the course in question and who had supplemental instruction. And this would be same as the sample. Here we can guess that this is a conceptual population - The students who might take the class and get SI.
b)Some students might be more motivated, and they might spend the extra time in the SI sessions and do better. Here they have done better anyway because of their motivation. There is other possibility that some students have weak background and know it and take the exam, But still do not do as well as the others. Here we cannot separate out the effect of the SI from a lot of possibilities if you allow students to choose.
The random assignment guarantees ‘Unbiased’ results - good students and bad are just as likely to get the SI or control.
c)There wouldn't be any basis for comparison otherwise.
Answer:
Step-by-step explanation:
f(x) = x^2 + 4x + 4
f(x + a) = (x + a)^2 + 4(x + a) + 4
f(x + a) = x^2 + 2ax + a^2 + 4x + 4a + 4 Now combine like terms and use the distributive property.
f(x + a) = x^2 + (2a + 4)x + a^2 + 4a + 4
We are told that f(x + a) = x^2 - 6x + 9
So that means that
2a + 4 = - 6 Subtract 4 from both sides.
2a = - 6 - 4
2a = - 10 Divide by 2
a = - 10/2
a = - 5.
But you are not finished. You have to check the last part.
a^2 + 4x + 4 = 9
(a + 2)^2 = 9
Take the square root of both sides
sqrt(a+ 2)^2 = +/- 3
a+2 = 3
a = 1.
Does this work or is it extraneous? It is extraneous because it will not work for 2(a) + 4 = - 6
You get 6 = - 6 which is not correct. But you did give the second best answer.
a + 2 = - 3
a = - 3 - 2
a = - 5 which agrees with your previous answer.
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This is an extremely hard or tricky or sneaky problem. It takes a lot of conniving to get the right answer and 1 is not a left field answer. It just does not happen to be correct.
Answer:
Primer número = x = 85
Segundo número = y = 255
Tercer número = z = 510
Step-by-step explanation:
Se sabe que la suma de tres números es 850. El primero es un tercio del segundo y el tercer número es el doble del segundo.
Representamos:
Primer número = x
Segundo número = y
Tercer número = z
Se sabe que la suma de tres números es 850.
x + y + z = 850 ...... Ecuación 1
El primero es un tercio del segundo
x = 1/3 años
El tercer número es el doble del segundo.
z = 2 años
Sustituimos 1 / 3y por x y 2y por z en la Ecuación 1
1 / 3y + y + 2y = 850
y / 3 + 3y = 850
Multiplica ambos lados por 3
y + 9y = 850 × 3
10 años = 2550
y = 2550/10
y = 255
Resolviendo para x
x = 1/3 años
x = 1/3 × 255
x = 85
z = 2 años
z = 2 × 255
z = 510
Por eso,
Primer número = x = 85
Segundo número = y = 255
Tercer número = z = 510
Answer:
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Step-by-step explanation:
