How many no of birds and animals ?

[rengaraj]

Sir / madam,
My question is

No. of animals is 11 more than the no. of birds. If the no. of birds were the no. of animals and no. of animals were the no. of birds (ie., interchanging no.s of animals and birds.), the total no. of legs get reduced by one fifth. How many no. of birds and animals were there

Advance Thanks,
R.Rengaraj
{SCE 35/2008/Pg 4 of 85}
{On this forum my 6th Question.}

[sookie]

Is the answer is Birds =11 and Animals=22 ?

[yadavundertaker]

let no. of animals = x
Let no, of birds = y

Acc to first condition

x=y+11

Acc to second condition

5(2x+4y )=4(4x+2y)

10x+20y=16x+8y
6x-12y=0

putting value of x from equation Ist

6(y+11)-12y=0
6y+66-12y=0
6y=66

y=11

then x=y+11

x=11+11=22

No. of animals =22
No of birds =11

[Guttu]

let no. of animals = x
Let no, of birds = y

Acc to first condition

x=y+11

Acc to second condition

5(2x+4y )=4(4x+2y)

10x+20y=16x+8y
6x-12y=0

putting value of x from equation Ist

6(y+11)-12y=0
6y+66-12y=0
6y=66

y=11

then x=y+11

x=11+11=22

No. of animals =22
No of birds =11

Nice explanation. I wonder how many of us apply what we learn?

[rengaraj]

Sir,
Thanks for your answer.
R.Rengaraj

[BigOhm]

Not to be overly pedantic, but aren't birds animals?

[gohm]

ha, yes and so are clams, fish and locust all of which would mess up the leg count. laugh. It is a good algebraic math puzzler though!