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# STUDENT AND TEACHER

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Senior Manager
Joined: 30 May 2005
Posts: 276
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14 Jun 2005, 05:54
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

.
hello
i found c
but how do you put this one into equation
i picked number 31 be the total number of student and teacher
hence 30 Students and 1 teacher
so 60 STUDENTS
AND 1+5 Teacher
right ? THANKS
The present ratio of students to teachers at a certain school is 30 to 1. If the student enrollment were to increase by 50 students and the number of teachers were to increase by 5, the ratio of students to teachers would then be 25 to 1. What is the present number of teachers ?
(A) 5
(B) 8
(C) 10
(D) 12
(E) 15
Manager
Joined: 28 Sep 2004
Posts: 82
Location: New York City
Followers: 1

Kudos [?]: 10 [1] , given: 0

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14 Jun 2005, 06:30
1
KUDOS
Mandy,

You can't plug in the numbers like this. The equations are as follows

EQ1
s/t = 30/1
s = 30t

EQ2
(s+50)/ (t+5) = 25/1
25(t+5) = S+50
25t + 125 - 50 = S
25t + 75 = 30t (since s = 30t from the first equation)
75 = 5t
t = 15

E

Now:
Manager
Joined: 06 Apr 2005
Posts: 53
Location: Germany
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14 Jun 2005, 06:54
well explained michalky. Totally agree with you.
Senior Manager
Joined: 30 May 2005
Posts: 373
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14 Jun 2005, 06:59
mandy wrote:
.
hello
i found c
but how do you put this one into equation
i picked number 31 be the total number of student and teacher
hence 30 Students and 1 teacher
so 60 STUDENTS
AND 1+5 Teacher
right ? THANKS
The present ratio of students to teachers at a certain school is 30 to 1. If the student enrollment were to increase by 50 students and the number of teachers were to increase by 5, the ratio of students to teachers would then be 25 to 1. What is the present number of teachers ?
(A) 5
(B) 8
(C) 10
(D) 12
(E) 15

Let the present number of students be s and present number of teachers be t.

"The present ratio of students to teachers at a certain school is 30 to 1" means:

s=30t

Second condition:

s+50 = 25(t+5) => s = 25t + 75

Solving it, we get

30t = 25t + 75

t=15

Senior Manager
Joined: 17 Apr 2005
Posts: 375
Location: India
Followers: 1

Kudos [?]: 23 [0], given: 0

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14 Jun 2005, 12:35
mandy wrote:
.
hello
i found c
but how do you put this one into equation
i picked number 31 be the total number of student and teacher
hence 30 Students and 1 teacher
so 60 STUDENTS
AND 1+5 Teacher
right ? THANKS
The present ratio of students to teachers at a certain school is 30 to 1. If the student enrollment were to increase by 50 students and the number of teachers were to increase by 5, the ratio of students to teachers would then be 25 to 1. What is the present number of teachers ?
(A) 5
(B) 8
(C) 10
(D) 12
(E) 15

Let the no. of teachers be x.
Then the no. of students are 30x.( use this fool proof technique for ratois).

Then after 50 students join , the total no. of students = 30x + 50
after 5 teachers join, their no would be = x + 5.

But the ratio now is 25/1.

ie (30x + 50)/(x + 5) = 25.

Solve for x to get to the answer.

HMTG.
Manager
Joined: 07 Mar 2005
Posts: 93
Followers: 1

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14 Jun 2005, 16:16
15 teachers as all have stated
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