Why?
2007-09-13 05:29:41 · 16 answers · asked by shade930 1 in Science & Mathematics ➔ Mathematics
It takes 3 minutes for a cat to kill a rat in this case.
To kill 30 rats will take 90 minutes total "cat activaty time"
90 minutes divided by 30 minutes = 3
Three cats can kill 30 rats in 30 minutes!
2007-09-13 05:45:36 · answer #1 · answered by fire4511 7 · 2⤊ 0⤋
If 3 cats kill 3 rats in 3 minutes that is a rat per cat. Since it took 3 minutes for 1 cat to kill one rat, 1 cat could kill 10 rats in 30 minutes. To kill 30 rats in 30 minutes this cat is going to need some help. If the first cat gets 10 rats in 30 minutes, the 2nd gets 10 rats in 30 minutes, and the 3rd gets 10 rats in 30 minutes that adds up to 30 rats in 30 minutes.
--- or just call an exterminator :-) ----
2007-09-13 05:37:59 · answer #2 · answered by Zefram 2 · 2⤊ 0⤋
I think the answer is 3.
If 3 cats require 3 mins to kill 3 rats, then 1 cat is taking is taking 3 minutes to kill 1 rat. (As there are 3 cats, in the 3-minute period, 3 rats are killed).
So in 30 mins, 1 cat would kill 10 rats, so you would still need 3 cats to get through 30 rats in a 30-minute period.
This is assuming that the cats don't take a breather between rats :-)
2007-09-13 05:53:45 · answer #3 · answered by Bruce Castle 2 · 1⤊ 0⤋
I don't htink it's as simple as saying "Oh because it takes 3 cats 3 minutes for 3 rats, then that must mean 1 cat kills one rat in 1 minute."
If each cat goes after one rat then it means it took each one 3 minutes for their rats.. on the other hand, if they all gang up on each rat chronologically, then each cat does 1/3 the killing, aka 20 seconds * 3 = 1 minute per cat?
I really think that they latter is the less likely of the two possibilities.
Therefore, I'm going to say 1 cat takes 3 minutes PER rat (not 1 minute because they aren't sharing each kill). That being the case, the answer should be, realistically, 3 cats offing 3 rats every 3 minutes for 30 minutes = 30 dead rats.
2007-09-13 05:48:32 · answer #4 · answered by RiceHunter 2 · 1⤊ 0⤋
Assuming that all cats will kill that amount of rats in the same time and all the other semplificative assupmtions, If we give to the following symbols the meaning:
r = number of killed rats
c = number of cats available
t = time given
Given the data we have, it would be=
r = (ct)/3
Infact, if we have three cats and three minutes to work with, the number of killes rats will be: r = (3*3)/3 = 3, which is exactly what it is said.
now, with the new data we see that r=30 and t=30, the unknown is c, the number of cats. The equation is the same as before, substituiting the values:
30 = (c*30)/3
Doing the calculations, you get:
1 = c/3
c=3
You need 3 cats, to kill that amount of rats in that amount of time, which is the same number of cats you had at the beginning. Good rat-hunting
2007-09-13 05:41:36 · answer #5 · answered by murrayskull05 2 · 2⤊ 0⤋
If you have a rat problem, cats are not the preferred course of action. Call an exterminator. In your question, 3 cats - 3 rats - 3 minutes breaks down into each cat killing a rat in 3 minutes. 1 cat therefore kills 10 rats in 30 minutes, requiring 3 cats for your 30 rats in 30 minutes. Unless of course those cats become bored, in which case it will take much longer or require many more cats. Don't feed the cats and they will kill the rats much quicker.
2007-09-13 05:39:38 · answer #6 · answered by Thegustaffa 6 · 0⤊ 2⤋
3 cats. 1 cat kills 1 rat in 3 minutes. Therefore in 30 minutes, 1 cat can kill 10 rats. So you'd need 3 of them to kill 30.
2007-09-13 05:36:54 · answer #7 · answered by Michael D 2 · 2⤊ 0⤋
3 cats in 3 minutes kill ---------- 3 rats
3 cats in 1 minute kill -------------- 1 rat
1 cat in 1 minute kill ------------ 1/3 rat
1 cat in 30 minutes kill ------------(1/3)*30
= 10 rats
so 10 rats can be killed in 30 minutes by ----- 1 cat
30 rats can be killed in 30 minutes by -------(1)(30)/10
= 3 cats
2007-09-13 05:46:41 · answer #8 · answered by mohanrao d 7 · 0⤊ 0⤋
30 cats.each cat kill a rat in one minute.
2007-09-13 05:35:02 · answer #9 · answered by oge 4 · 0⤊ 3⤋
rats / (speed in minutes * time) = no. of cats needed
= 30 rats / ([3 min / 3 cats] * 30 min)
= 30 rats / (1 rat per min * 30 min)
= 30 / 30
= 1
Answer: 1 cat is needed
Proof:
= 1 cat * 30 min
= 30 rats
2007-09-13 05:45:48 · answer #10 · answered by Jun Agruda 7 · 3⤊ 2⤋