79. Students of a class are standing in row. If number
of students in a row is increased by 3 then the
number of row is decreased byl and if number of
students in row is decreased by 3 the number of
row is increased by 2. The number of students in
the class are
(A) 36
(B) 26
(C) 16
(D) 46
explain in brief
Answers
Answer:36 student
Step-by-step explanation:
Answer:
(A) : 36 people
Step-by-step explanation:
Okay, the students are initially in a particular arrangement.
* Let's say that the initial arrangement has x rows.
1st condition :
Each row +3 students = -1 row
Let's say the last row is removed, so no. of rows = x-1
Each of these x-1 rows has 3 extra students
* Therefore, no of extra students in all rows = 3(x-1)
These must be the students of the last row.
Therefore, no of students in each row "initially" = 3(x-1)
* So, no of total students is x * 3(x-1) = x * (3x-3)
2nd Condition :
Each row -3 students = +2 rows
No of students in each row "initially" = 3(x-1) = 3x-3
* No of students in each row after condition = 3x-6
No of rows "initially" = x
* No of rows after condition = x+2
* So, No of students now = (3x-6)*(x+2)
Clearly, Initally and finally no. of students is same
So, x * (3x-3) = (3x-6)*(x+2)
=> 3x^2 - 3x = 3x^2 + 6x - 6x - 12
=> -3x = -12
=> x = 4
If x is 4 then no of students in each row initially is
3(x-1) = 3(4-1) = 3(3) = 9
So, no of students is (rows * students in each row)
= 4*9 = 36 ///