Question

Students were standing in rows for P.T. exercise. If 4 students were less in each row, 10 more rows
were required and if 5 students were more in each row then number of rows was reduced by 8. Find
the number of students. [Students = 800]

Answer 1

Answer:

Let the number of rows be x and number of students in each row be y

Then total students will be=x*y

Now according to question

(x+10)(y-3)=xy

xy-3x+10y-30=xy

10y-3x=30-----------------(eq1)

Now..

(x-10)(y+5)=xy

xy+5x-10y-50=xy

5x-10y=50 ---------------(eq 2)

Adding eq 1 and 2 we get

2x=80

x=40

Putting x=40 in eq 1 we get

10y-120=30

10y=150

y=15

4.8

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Answer 2

Answer:

800

Step-by-step explanation:

Number of students in a row- s

Number of rows- r

Total number of students- rs

As per given we have 2 equations,

• (s-4)(r+10)=rs => sr+10s-4r-40=rs => 10s-4r=40
• (s+5)(r-8)=rs => sr-8s+5r-40=rs => -8s+5r=40

Combining above 2 equations:

• 10s-4r=-8s+5r => 18s=9r => r=2s

Considering this in 1st equation:

• 10s-4*2s=40 => 2s=40 => s=20 - students per row
• r=2s=40 - number of rows

Total number of students rs= 20*40=800