Maths- Gym for Brainiacs

she spirals towards shore and keeps herself exactly half a circle ahead of the rapist, once she reaches the radius at which her speed and the rapists are the same she goes towards the shore in a straight line, giving her enough headstart

numerical results incoming soon btw

spanky489 wrote:she spirals towards shore and keeps herself exactly half a circle ahead of the rapist, once she reaches the radius at which her speed and the rapists are the same she goes towards the shore in a straight line, giving her enough headstart

numerical results incoming soon btw

Their absolute speeds are never the same. You meant the angular velocity I guess
As far as the answer goes, absolutely correct but without the numbers unacceptable Once you get the numerical part right, you win

Kamina wrote:

spanky489 wrote:she spirals towards shore and keeps herself exactly half a circle ahead of the rapist, once she reaches the radius at which her speed and the rapists are the same she goes towards the shore in a straight line, giving her enough headstart

numerical results incoming soon btw

Their absolute speeds are never the same. You meant the angular velocity I guess
As far as the answer goes, absolutely correct but without the numbers unacceptable Once you get the numerical part right, you win

yea their angular velocities will be same when she is at 0.25*r and then she has 0.75*r to do in a straight line, but because she is 180 degrees shifted from the rapist, he has to do pi but 0.75*4 < pi

she would escape narrowly, with her keister almost in reach to the rapist

spanky489 wrote:

Kamina wrote:

spanky489 wrote:she spirals towards shore and keeps herself exactly half a circle ahead of the rapist, once she reaches the radius at which her speed and the rapists are the same she goes towards the shore in a straight line, giving her enough headstart

numerical results incoming soon btw

Their absolute speeds are never the same. You meant the angular velocity I guess
As far as the answer goes, absolutely correct but without the numbers unacceptable Once you get the numerical part right, you win

yea their angular velocities will be same when she is at 0.25*r and then she has 0.75*r to do in a straight line, but because she is 180 degrees shifted from the rapist, he has to do pi but 0.75*4 < pi

she would escape narrowly, with her keister almost in reach to the rapist

It wasn't that hard, wasn't it? You forgot to add, she gains ground on him if she swims circular with a radius R<0.25r and she loses ground if she swims with R>0.25
P.S. you'd make a proper rapist, a real keister chaser

Good stuff Spanky!

kiranr wrote:
Good stuff Spanky!

thx couldnt have done it without u and the other boys though. also sometimes to solve a problem u just need to sleep it over. i cant even count the number of times i didnt know the answer to an exam question and then in the span of a few days post the exam i would wake up in bed with the answer in my head.

I don't know how hard my questions are therefore I'll test them on I-no If she takes between 1-4 minutes to solve them= easy, between 4-6 minutes= medium, between 7-10 hard and above 10 minutes very hard


Next question
difficulty: easy (2 minutes)
requirements: junior high level
Shorty Jack walks his dog on the beach in early morning. From afar, he sees his best friend, Lanky Dani They start walking towards each other. While they walk Shorty's dog keeps going back and forth between both friends until they shake hands
The initial distance between Shorty Jack and Lanky Dani was 20m. Shorty walks with 2 m/s, Lanky with 3 m/s and the dog with 5m/s (velocities). To make your internet lives easier, assume that their velocities are constant
The question: how much distance did the dog cover in the process?

kiranr wrote:
Good stuff Spanky!

The lurker!

Jack and Dani meet 4 seconds in.

The dog reaches Dani at 3 seconds, then goes back to Jack at 4 seconds, covering 14 meters.

Wrong

dog covered 20 meters. easy.

spanky489 wrote:dog covered 20 meters. easy.

Give a complete answer (lurkers)

4 seconds it takes for them to meet, 4* 2m/s = 8 , 4 * 3 m/s = 12 8+12 = 20
4 seconds * 5 m/s = 20, this is the straightforward answer but, there are ways to complicate this problem.

Well if the dog is a retard, then yes he covers 20m.

Timeline:
At 1 second:
Assuming halfline is 0.
Jack goes -8, Dani 7

At 2 seconds:
Jack -6, Dani 4

At 3 seconds:
Jack -4, Dani 1

at 4:
J -2, D -2. Here they meet.

4 seconds * 5m/s = 20m.

next question: statistics
requirements: junior high school
difficulty: unknown

Spanky will have two kids in upcoming 5-6 years. One of them is a son. How high is the the possibility that his son will have a brother?

spanky489 wrote:4 seconds it takes for them to meet, 4* 2m/s = 8 , 4 * 3 m/s = 12 8+12 = 20
4 seconds * 5 m/s = 20, this is the straightforward answer but, there are ways to complicate this problem.

If two objects move towards each other, you can add their velocities( I-no's way)
20/(2+3)=4 then 4*5=20

1) distance between them is 20

so you have to find an equilibrium when both(+the dog) meet at the same second and what length that is

after the first second:

Shorty has 2 and Lanky 3

after the second one:

Shorty has 4 and Lanky 6

after the third second:

shorty has 6 and lanky 9

and after the fourth second:

Shorty 8 and Lanky 12

since the dog covers 5 metres in one second he reaches the 20th metre after 4 seconds which is exactly at the same time as the two friends so the all meet up

Kamina wrote:next question: statistics
requirements: junior high school
difficulty: unknown

Spanky will have two kids in upcoming 5-6 years. One of them is a son. How high is the the possibility that his son will have a brother?

there are two sexes boy or a girl.... since they already got a boy first the next chance of getting a boy is 1/3

halamadrid2 wrote:

Kamina wrote:next question: statistics
requirements: junior high school
difficulty: unknown

Spanky will have two kids in upcoming 5-6 years. One of them is a son. How high is the the possibility that his son will have a brother?

there are two sexes boy or a girl.... since they already got a boy first the next chance of getting a boy is 1/3

Good job hala and you said you hated statistics Your probability is right but the argumentation is wrong, correct it

Kamina wrote:

halamadrid2 wrote:

Kamina wrote:next question: statistics
requirements: junior high school
difficulty: unknown

Spanky will have two kids in upcoming 5-6 years. One of them is a son. How high is the the possibility that his son will have a brother?

there are two sexes boy or a girl.... since they already got a boy first the next chance of getting a boy is 1/3

Good job hala and you said you hated statistics Your odd is right but the argumentation is wrong, correct it

arright basically in a family there are four possible combos

boy and girl
boy and boy
girl and girl
girl and boy

since youve already gotten a boy as you said you cant get two daughters obviously

so you delete that from it all, and you have the rest left

Boy and Girl

Boy and Boy

Girl and Boy

the one in the middle is what you want therefore the probability of getting two boys from a total of three possibilities is 1/3

better??

Next question

topic: analysis
difficulty: very hard
requirements: junior high level

Hala2 is hungry. He opens his refrigirator and doesn't find anything With no choice left, he goes to the closest super market
He buys his stuff and pays with a 100€ bill. The cashier confuses euros and cents while giving the drawback. While Hala2 packs his stuff into bags, he loses 5 cents on the ground without noticing. At home, he notices that he's got twice the amount of drawback he should've gotten in the first place
How high was his super market bill initially?

Kamina wrote:Next question

topic: analysis
difficulty: unknown ( not tested on I-no)
requirements: junior high level

Hala2 is hungry. He opens his refrigirator and doesn't find anything With no choice left, he goes to the closest super market
He buys his stuff and pays with a 100€ bill. The cashier confuses euros and cents while giving the drawback. While Hala2 packs his stuff into bags, he loses 5 cents on the ground without noticing. At home, he notices that he's got twice the amount of drawback he should've gotten in the first place
How high was his super market bill initially?

1 Euro is 100 Cents

he pays with 100 Euros and loses 5 cents which is 1/20 Euros

take away that from the initial and youve got 99.95 Euros

is the initial bill around 60/5

halamadrid2 wrote:

Kamina wrote:Next question

topic: analysis
difficulty: unknown ( not tested on I-no)
requirements: junior high level

Hala2 is hungry. He opens his refrigirator and doesn't find anything With no choice left, he goes to the closest super market
He buys his stuff and pays with a 100€ bill. The cashier confuses euros and cents while giving the drawback. While Hala2 packs his stuff into bags, he loses 5 cents on the ground without noticing. At home, he notices that he's got twice the amount of drawback he should've gotten in the first place
How high was his super market bill initially?

1 Euro is 100 Cents

he pays with 100 Euros and loses 5 cents which is 1/20 Euros

take away that from the initial and youve got 99.95 Euros

is the initial bill around 60/5

Wrong by a huge margin It took me 7 minutes to solve it. Time to label the question as very hard

was thinking the same lol it confused me...give me 10 more mins and ill solve it

basically did he giive him it all in cents or some cents and some euros??

He gave him cents in place of euros and euros in place of cents. For example, instead of 12.63€ he gave 63.12€

ohh i see... made it clearer now