Mathematics Question Thread

[amelia20181]

for part c in the this question why cant you do 1- probability of no arrows hitting the target

The probability of an arrow hitting a target is 85%. If 3 arrows are shot, find the probability as a percentage, correct to 2 decimal places, of a) all arrows hitting the target b) no arrows hitting the target c) at least one arrow hitting the target 

[jamonwindeyer]

for part c in the this question why cant you do 1- probability of no arrows hitting the target

The probability of an arrow hitting a target is 85%. If 3 arrows are shot, find the probability as a percentage, correct to 2 decimal places, of a) all arrows hitting the target b) no arrows hitting the target c) at least one arrow hitting the target 

You can do that! 1 - the answer from (b) should be correct

[fun_jirachi]

100 tickets, 2 prizes.
Each ticket has \(\left(\frac {1} {50} \right ) \) chance of winning a prize.
Anna has 4 tickets.

P= \(\frac {4} {50} \)

I dunno about this, because part a) saying first prize made me think there's a second prize, so like maybe there isnt an equal chance of winning them ie. second prize is drawn after the first prize.
If Alan wins first prize only its 4/100x96/99 and second prize only is 96/100*4/99, so its 768/9900? idk, might be wrong
EDIT: in bold, i previously wrote 792 because i can't type properly on a calculator the new answer cancels down to the 64/825 you want

[amelia20181]

The answer is 64/825 but i don't know how to get it

[S200]

The answer is 64/825 but i don't know how to get it

I dunno about this, because part a) saying first prize made me think there's a second prize, so like maybe there isnt an equal chance of winning them ie. second prize is drawn after the first prize.
If Alan wins first prize only its 4/100x96/99 and second prize only is 96/100*4/99, so its 768/9900? idk, might be wrong
EDIT: in bold, i previously wrote 792 because i can't type properly on a calculator the new answer cancels down to the 64/825 you want

Hmm. I need to rework my maths...  sorry...
Lucky New south Welshmen are smarter!

[amelia20181]

 Thankss!


for real roots is the discriminant greater than or equal to zero

do the cambridge  and fitzpatrick textbooks have worked solutions for all the answers   



would this question be a band 6 type

[jamonwindeyer]

for real roots is the discriminant greater than or equal to zero

Yep! Otherwise you have the square root of a negative, which for 2U is total nonsense

do the cambridge  and fitzpatrick textbooks have worked solutions for all the answers   

Pretty sure it is just solutions, no working, for both

would this question be a band 6 type

Yeah for sure, testing your ability to adapt to a new situation of the same type!

[amelia20181]

For part c in this question can you do 1- probability of not breeding any albinos

[fun_jirachi]

For part c in this question can you do 1- probability of not breeding any albinos

Yes you can!

[amelia20181]

oh i tried that but i got the wrong answer

[fun_jirachi]

You should be getting this:

[amelia20181]

yea thats what i got the answer says its 35929/35937

[fun_jirachi]

Well the answer is wrong, because that is the chance of having two albinos or less, or  1 - the chance of having all albinos.
Sometimes, if the answer doesnt make sense after an hour or so, you're probably right.

[amelia20181]

how would you do this question

[jamonwindeyer]

how would you do this question

You really don't have the information you'd need to know for sure, but the answer would be 'incorrect.' Bill is assuming they would actively not choose numbers 1 through 6, when in reality, even that highly coincidental combo has a chance of appearing