Solve these

Calculus Level 2

You have 100 rupees and you want to buy 100 birds which must include at least one from each of the three kinds below.

  • 1 parrot for 5 Rs
  • 1 crow for 1 Rs
  • 20 sparrows for 1 Rs

If p p , c c and s s are the numbers of parrots, crows and sparrows that you buy respectively, give your answer as p + c − s p+c-s .


The answer is -60.

Kshitij Rathod by Kshitij Rathod , 16, India

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

2 solutions

Parth Sankhe
Nov 13, 2018

Let x x =number of parrots bought, y y for crows and z z for sparrows.

We have two equations,

x + y + z = 100 x+y+z=100 :-Number of birds

5 x + y + z 20 = 100 5x+y+\frac {z}{20}=100 :- Cost of the birds

This gives us 5 x + z 20 = x + z 5x+\frac {z}{20}=x+z

z = 80 x 19 z=\frac {80x}{19}

Since all three are integers, x x will have to be a multiple of 19. Fortunately, only x=19 satisfies this system, since any other x will result in a negative y y .

∴ x = 19 , z = 80 , y = 100 − 80 − 19 = 1 \therefore x=19,z=80,y=100-80-19=1

3 Helpful 0 Interesting 0 Brilliant 0 Confused
Kshitij Rathod
Nov 13, 2018

19=95 1=1 80=4

0 Helpful 0 Interesting 0 Brilliant 0 Confused

@Kshitij Rathod , I have changed the answer option to number so that members cannot go through all the answer options and find the answer.

Chew-Seong Cheong - 2 years, 7 months ago

1 pending report

Vote up reports you agree with

×

Problem Loading...

Note Loading...

Set Loading...