Question

The number of birds on each of the islands X and Y remains constant from year to year; however, the birds migrate between islands. After one year, 20 percent of the birds on X have migrated to Y, and 15 percent of the birds on Y have migrated to X. ?

If the total number of birds is 14, 000, how many birds are on island X????

the options given are
A) 2,800
b) 6,000
c) 6,788
d) 7,212
e) 8,000

Answer 1

Let the number of birds in island X be `n`. So the number of birds in `Y` will be `14000-n`.

After one year, 20 percent of the birds on X have migrated to Y, and 15 percent of the birds on Y have migrated to X.
But the number of birds on each of the islands X and Y remains constant from year to year;

So

`n*20/100=(14000-n)*15/100`

`=>35n=14000*15`

`=>n=14000*15/35=6000`

Hence number of birds in `X` will be `6000`