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All 48 seniors in a certain high school take one of two English classe

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Bunuel
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All 48 seniors in a certain high school take one of two English classe [#permalink] New post   03 Mar 2020, 01:38
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All 48 seniors in a certain high school take one of two English classes. What is the average (arithmetic mean) height of the seniors in this school?

(1) In the school, the average height of the seniors in the English class with the larger number of students is 70 inches

(2) In the school, the average height of the seniors in the English class with the smaller number of students is 4/5 of the average height of the seniors in the other English class
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Re: All 48 seniors in a certain high school take one of two English classe [#permalink] New post   03 Mar 2020, 01:52
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(1) We don't know the average height and the number of the seniors in the English class with the smaller number of students. In addition, we don't know the number of the seniors in the English class with the larger number of students.
NOT SUFFICIENT

(2) We don't know the average height and the number of the seniors in the English class with the larger number of students. Additionally, we don't know the average height and the number of the seniors in the English class with the smaller number of students.
NOT SUFFICIENT

(1)+(2)
We only know that 70in and 56in are the average height of the seniors in the English class with the larger number of students and the smaller one, respectively. We still don't know the number of the seniors in each of the two English classes.
NOT SUFFICIENT.

FINAL ANSWER IS (E)

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Re: All 48 seniors in a certain high school take one of two English classe [#permalink] New post   03 Mar 2020, 07:35
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Total number of Seniors in Both classes, A and B, = 48, An+Bn=48------(1)
We are to find the average height of the Seniors in the School.

1. In the school, the average height of the seniors in the English class with the larger number of students is 70 inches
Clearly insufficient. We need to know the average height of the other class and the number in each class in order to determine the average height.

2. In the school, the average height of the seniors in the English class with the smaller number of students is 4/5 of the average height of the seniors in the other English class
Statement 2 gives us a relationship between the average heights of the two classes. This is clearly not enough. We need to know the actual height of students in the larger class and the number of students in the classes in order to determine the overall average.

1+2
Both statements taken together still lack a key requirement in determining the average height. We still have no information on the number of students in the classes. Merely knowing that the total students in both classes is 48 and that one class larger in terms of the number of students is not enough. Both statements even when taken together are not sufficient.

The answer is E.
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Re: All 48 seniors in a certain high school take one of two English classe [#permalink] New post   03 Mar 2020, 07:39
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Quote:
All 48 seniors in a certain high school take one of two English classes. What is the average (arithmetic mean) height of the seniors in this school?

(1) In the school, the average height of the seniors in the English class with the larger number of students is 70 inches

(2) In the school, the average height of the seniors in the English class with the smaller number of students is 4/5 of the average height of the seniors in the other English class


average=sum*n
average=sum(A+B)/48

(1) insufic
A/(48-x)=70

(2) insufic
B/x=0.8A/(48-x)

(1/2) insufic
B/x=0.8(70)=56…B=56x
A/(48-x)=70…A=70(48-x)
Average: 56x+70(48-x)/48=70(48)-15x/48
x=?

Ans (E)
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Re: All 48 seniors in a certain high school take one of two English classe [#permalink] New post   03 Mar 2020, 09:38
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class 1 + class 2 = 48
let total class 1=x and class= y
so x+y=48
find total sum of class x+y height/48 = avg height


#1In the school, the average height of the seniors in the English class with the larger number of students is 70 inches


let x >y
so sum of height of x/48-y = 70
x & y not know insufficient
#2
In the school, the average height of the seniors in the English class with the smaller number of students is 4/5 of the average height of the seniors in the other English class
avg of y ; sum of y height/( 48-x) = 4/5 * avg height of sr in other class
insufficient
from 1 &2
sum of y height/( 48-x) = 4/5 * (70)
x & y are still not know
insufficient
IMO E


All 48 seniors in a certain high school take one of two English classes. What is the average (arithmetic mean) height of the seniors in this school?

(1) In the school, the average height of the seniors in the English class with the larger number of students is 70 inches

(2) In the school, the average height of the seniors in the English class with the smaller number of students is 4/5 of the average height of the seniors in the other English class
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Re: All 48 seniors in a certain high school take one of two English classe [#permalink] New post   03 Mar 2020, 23:52
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average (arithmetic mean) height of the seniors in this school = (avg height of larger number of students * no.of students in that class + avg height of smaller number of students * no.of students in that class) / 48

(1) In the school, the average height of the seniors in the English class with the larger number of students is 70 inches............we need 3 more parameters to determine the avg height of school.......INSUFFICIENT

(2) In the school, the average height of the seniors in the English class with the smaller number of students is 4/5 of the average height of the seniors in the other English class........we dont the no.of students in each class......INSUFFICIENT

Even after combinig both we dont have the count of the students in each class....

OA:E
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Re: All 48 seniors in a certain high school take one of two English classe [#permalink] New post   03 Mar 2020, 21:33
All 48 seniors in a certain high school take one of two English classes. What is the average (arithmetic mean) height of the seniors in this school?

(1) In the school, the average height of the seniors in the English class with the larger number of students is 70 inches

(2) In the school, the average height of the seniors in the English class with the smaller number of students is 4/5 of the average height of the seniors in the other English class
Solution:
To be calculated: (x+y)/48 = ?
Let,
The average height of the seniors in the English class with the larger number of students = x
The average height of the seniors in the English class with the smaller number of students = y
From Statement (1), x= 70, There is no value of y. Hence ,Not sufficient.
From Statement (2), y = 4x/5, There is no value of x.

Combining statements 1 and 2, we find the value of x and y. Hence, Sufficient.
Answer: C
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Re: All 48 seniors in a certain high school take one of two English classe [#permalink] New post   10 Mar 2024, 02:24
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Re: All 48 seniors in a certain high school take one of two English classe [#permalink]
10 Mar 2024, 02:24
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