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Can you find the error?

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6
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(kind of offf-topic, but its close enough to be a math question) Its so annoying to make silly mistakes, a long though-out solution to a problem can turn out to be wrong because of a simple human error.

Here is an example of how I failed a problem: (these are the types of mistakes i make.)

"Aaron and Jackson have a large number of pets: fish, cats and chickens. The pets have a total of 50 legs, 48 eyes and 6 wings. Assuming each cat has 4 legs, each chicken has 2 legs and 2 wings, and each pet has 2 eyes, how many pets do Aaron and Jackson have?"

According to the problem, there are 6 wings and no other animal has wings. So since chickens have 2 wings, there are THREE chickens.

Since chickens have 2 eyes and 2 legs, we can do 3 * 2 = Subtract 6 from 50 legs and 48 eyes

So we have 44 legs and 42 eyes.

Cats have 4 legs, so there must be 44/4 = 11 cats (fish have no legs)

11 cats * 2 = 22 eyes.

So 42-22 = 20 eyes left.

20 eyes, and fish have two eyes, so 22/10 = 2 fish.

The number of pets is 6 chickens + 11 cats + 2 fish = 19 animals. (do you see the error?)

Double checking DOES NOT work, as in a competition, there is NO TIME.

Do you guys have any tips on getting a problem right the FIRST time you do it?

You can see how recently in my answers on this website I have been making silly errors.

Nov 8, 2019
edited by CalculatorUser  Nov 8, 2019
edited by CalculatorUser  Nov 8, 2019

#1
+1

"20 eyes, and fish have two eyes, so 22/10 = 2 fish".

This is where your mistake is: 20 eyes for the fish, 20 / 2 =10 fish

So, 10 fish + 11 cats + 3 birds =24 pets.

Nov 8, 2019
#2
+276
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You said: "According to the problem, there are 6 wings and no other animal has wings. So since chickens have 2 wings, there are THREE chickens.

Since chickens have 2 eyes and 2 legs, we can do 3 * 2 = Subtract 6 from 50 legs and 48 eyes

So we have 44 legs and 42 eyes.

Cats have 4 legs, so there must be 44/4 = 11 cats (fish have no legs)

11 cats * 2 = 22 eyes.

So 42-22 = 20 eyes left.

20 eyes, and fish have two eyes, so 22/10 = 2 fish.

The number of pets is 6 chickens + 11 cats + 2 fish = 19 animals. (do you see the error?)

The right answer: There are 48 eyes, and that means there are 24 pets in total...

each animal has two eyes! 48/2=24!

What you got wrong: it is highlighted above. For the Fish, you said there are 20 eyes left and fish have two eyes, that is right, but later, you did 22/10 instead of 20/2. there are 10 fish. For the final answer, you said The number of pets is 6 chickens + 11 cats + 2 fish = 19 animals​, but I believe you also said that there are 3 chickens---not 6. LOL. The right answer is: The number of pets is 3 chickens+11cats+10fish=24 animals. (you understand now?)

Nov 8, 2019
#3
+1

This is a weird question

Nov 8, 2019
#4
+2850
+1

I knew my mistake lol

I just wanted some tips on how NOT to make mistakes

Sorry I worded my title wrong

- No "bullrushing", don't rush your answer once you have an idea, think it through.

- "Mental Check" Different from double checking, this a method where you mentally check if every step in your solution is practical, makes sense, and mathematicall is right (if you can) AS YOU DO IT

- Ask your self the question: "What is the 'problem' of the Problem?". What is the answer you are trying to find?

- Check for traps. For example, a problem might have "label the units" at the end of it, and you might not notice. These are "traps" that can be avoided.

-Neat and tidy. When doing work on paper, keep everything clear so its easier to do the "mental check" and avoids silly reading and calculation errors.

CalculatorUser  Nov 8, 2019
#5
+276
0

Thanks for the tips. People always make mistakes...

Like me... see this... https://web2.0calc.com/questions/helppp-meee-im-soo-stuck

Nov 8, 2019
#6
+2850
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Me too!
I make many!

These are the two out of (dozens?) mistakes I made

https://web2.0calc.com/questions/competition-math#r3

https://web2.0calc.com/questions/help_92148#r1 this is a big one

CalculatorUser  Nov 8, 2019