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In a school of 1200 students, the ratio of

the number of teachers to students is 1 : 15.
After some teachers join the school, the ratio of
the number of teachers to students becomes 3:40.
Find
(i) the initial number of teachers in the school,
(ii) the number of teachers who join the school.​

User DeeDee
by
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2 Answers

7 votes
No. Of Teachers Initially = 80
No. of Teachers joined = 10
User Serak Shiferaw
by
8.9k points
6 votes

Explanation:

i)Initial School population,

given 15 units = 1200

1 unit =


1200 / 15 \\ = 80

Number of teachers (initial) = 1 unit = 80.

ii)take j = number of teachers joining the school.

New teacher population = 80+j


(3)/(43) (1280 + j) = 80 + j \\ (3840)/(43) + (3)/(43) j = 80 + j \\ j - (3)/(43) j = (3840)/(43) - 80 \\ (40)/(43) j = (400)/(43) \\ 40j = 400 \\ j = 400 / 40 \\ = 10

User Mohammed Hassan
by
7.3k points

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