[Rabbit]

1. A coin has been weighted so that the probablility of gettting heads is 2/5 and tails 3/5. The coin is thrown twice. What is the probablility of obtaining.

A) 2 heads. (is it 2/5 x 2/5)
B) no heads. (is it 3/5 x 3/5)
C) At least one heads.
Pretty sure i no a + b but not sure about c. and pls tell how you get it.

2. A spinner has 3 parts red 1 part Blue. it is spun twice.
a) what is the probability of getting two reds
b) at least one red
c) no reds.

[Badboi]

Answer is 'B' I think.

[SmG Phoenix]

So for 1.c.
Probability of getting heads first then tails or tails first then heads does not matter, meaning the order is not important.
Therefore, probability of tails then heads is:
(2/5)*(3/5)
This is the same for heads then tails.
Then using the answer from a. we can get an overall equation of:
(2/5)*(3/5)*2+(2/5)*(2/5)
So, 0.48+0.16=0.64
2. 3/4 chance of red getting in any random spin.
Therefore (3/4)*(3/4)
which gives an answer of 0.5625
b. Probability is again similar to question 1.c
(3/4)*(3/4)+(3/4)*(1/4)*2
This gives an answer of 0.9375
c. This question is basically the inverse of the previous question.
Two methods can be used to approach this question.
The first is that we know a chance of any given event occurring is 1. Therefore, we can simply get:
1-0.9375=?
The previous calculation is the probability of everything else that can happen.
The other methods is simply (1/4)*(1/4)=?
Both answers come out to be 0.0625. I would personally use the first method and use the second for a proof check.
I hope this helps. I do Unit 1&2 Methods with an average of 90%! :D So ask me anything maths related and I do have Unit 3&4 Methods as well, but not as solid. I hope my language was not too difficult to understand.

[Rabbit]

(2/5)*(3/5)*2+(2/5)*(2/5)
So, 0.48+0.16=0.64

why do you have to times it by 2 in (2/5)*(3/5)*2. and 64% looks right to me :) :BaNaNa:

[SmG Phoenix]

If I obtain heads first it does not decrease or increase my chance of a tails later on. The same goes for if I obtain tails first. So for 1 head, we can either of 2 possibilities.
They are:
Heads then tails.
Tails then heads.
Therefore, there are 2 possibilities hence the multiplication of 2.

[SmG Storm]

did all the questions then i read phoenix's post...
FML

[SmG Phoenix]

If you could explain it better, you must have written some Maths textbook sometime in your life. XD

[Alloy]

did all the questions then i read phoenix's post...
FML

Does that mean "fuck my life"?

Anyway, i think the answer for the second question is b.

[SmG Dragonrage]

Nice work Phoenix. I would have explained it about the same way but maybe not as clear. Also if anyone needs help with math I can help as well. I know up to calculus 3(aka calc c) and statistics. Am taking multivariable calc now but don't have a full enough understanding as of yet to help ppl

[Beasty]

Dude......we do this shit in like 4th grade......i dont want to hear anyone say anything negative about american education :p

That being said: i honstly dont remember much of it tbh, kinda a fail on my part.

But this stuff is pretty easy- god i hate algebra 2. Such a load of BS. Who cares about imaginary numbers and finding the Y intercept of a slope of a line >:(

Hurr durr

i = i^5 = i^10

Because with "imaginary numbers" you multiply a variable to the power of 1 and five and still end up with the same answer; 1i

Seems legit