aaman1 wrote:
Can someone help with these questions:
Q1. We have ducks and pigs in a field ? There are 30 creatures in all. All the legs add up to 92. a)how many ducks? b) How many pigs?
16 pigs and 14 ducks (16 x 4 + 14 x 2 = 92). I did it graphically (draw 2x + 4y = 92 and x + y = 30, where they cross is the answer) but you can do it algebraically as well:
4p + 2d = 92
p + d = 30
2p + 2d = 60 (multiply second equation by 2)
2p = 32 (subtract from first equation)
so p = 16, and so d = 14.
As it happens, you can do it very quickly by trial and error, too. Suppose there's 15 of each: 90 legs. So we need two more legs. Swap a duck for a pig and there you are.