emaths probability

bratorbread SG

amy either walks or cycles to school each morning . the probability that she walks is 2/3 . when she walks , the probability that she is late is 1/9 . when she cycles , the probability that she is late is 4/9 .

find the probability that she is late.

i cant seems to get ans right

FireIce SG

P(cycle) = 1 - 2/3 = 1/3
P(cycle and late) = 1/3 x 4/9 = 4/27
P(walk and late) = 2/3 x 1/9 = 2/27

P(walk and late OR cycle and late) = 4/27 + 2/27 = 2/9

bratorbread SG

yeah but the answer is 6/27 ..

answer wrong?

^Acid^ aka s|aO^eH~ SG

2/9 and 6/27 same ah... u must simpify...

FireIce SG

yeah but the answer is 6/27 ..

answer wrong?

reduce to simplest terms

bratorbread SG

oh yeah! thx haha didnt notice.

kenn3th SG

@ bread

u seem very tensed up are u ?

bratorbread SG

yeah 2 mre weeks till o's

SBS n SMRT SG

but some out of topic stuff

qns seems faulted, why walk less likely to be late than cycle

In topic

In recent syllabus change , no longer need to present ans in P(E) where e is event, now just write Probability: ...(blah blah blah)... can liao

bratorbread SG

its one of the questions from 2006 tys haha

yiha093 SG

its one of the questions from 2006 tys haha

no wonder so familiar x.x

gunner77 SG

wow

queen of sgforum help u solve leh..

means the question very easy.

bratorbread SG

haha.

some other questions which i dun get it...

given tat (3x-1)(x+p)=3x^2 +qx -2

find p,

find q.

the force F , between 2 particles are inversely proportional to the square of the distance between them.

the force is 36 units when the dist. between the particles are r metres.

find the force when the distance is 3r metres.

dkcx SG

haha.

some other questions which i dun get it...

given tat (3x-1)(x+p)=3x^2 +qx -2

find p,

find q.

the force F , between 2 particles are inversely proportional to the square of the distance between them.

the force is 36 units when the dist. between the particles are r metres.

find the force when the distance is 3r metres.

Expand (3x-1)(x+p) then just compare coefficients with the right hand side equation to solve for p and q.

F = k/(dist^2)
36=k/(r^2)
k=36r^2

F = (36r^2) / ((3r)^2)
= 36r^2 / 9r^2
= 4

TrueHeart SG

haha.

some other questions which i dun get it...

given tat (3x-1)(x+p)=3x^2 +qx -2

find p,

find q.

the force F , between 2 particles are inversely proportional to the square of the distance between them.

the force is 36 units when the dist. between the particles are r metres.

find the force when the distance is 3r metres.

Hi bratorbread,

For the first question, are the two sides equivalent?

For the second question, what they mean is F = k/(D^2), where k is a constant, and D is the distance.

What we have is that 36 = k/(r^2).

Hence, when D = 3r, we will have F = k / (3r)^2 = k / 9(r^2) = 36/9 = 4 units.

Cheers.

bratorbread SG

when i expand it out i get 3x^2 + 3xp -x -p = 3x^2 + qx -2

i still dun get the values of p and q

idk the question did not state tat both sides are equivalent or not

dkcx SG

when i expand it out i get 3x^2 + 3xp -x -p = 3x^2 + qx -2

i still dun get the values of p and q

idk the question did not state tat both sides are equivalent or not

From the equation, u can already get p since p = 2 by comparing coefficient of the constant on both side.

With p u better be able to get q if not u will really need alot of help with ur maths

TrueHeart SG

when i expand it out i get 3x^2 + 3xp -x -p = 3x^2 + qx -2

i still dun get the values of p and q

idk the question did not state tat both sides are equivalent or not

Hi bratorbread,

Did they used = or = for the two polynomials?

Cheers

dkcx SG

Hi bratorbread,

Did they used = or = for the two polynomials?

Cheers

Such questions are always equivalent if not it can't be solved

bratorbread SG

just = .

when p = 2 den

3x^2 + 5x -2 = 3x^2 + qx -2

so q = 5 ?