Probability

[monokekie]

2. A random variable X has probability denisty function f with the rule:

Show that is an antiderivative of and hence find the interquartile range of X.

WHY IS THIS QUESTION SO WIERED?
there should be a solution according to its graph, however, the interquantile values don't seem real.

could somebody pls solve it? intrigued..

[ed_saifa]

2. A random variable X has probability denisty function f with the rule:

Show that is an antiderivative of and hence find the interquartile range of X.

WHY IS THIS QUESTION SO WIERED?
there should be a solution according to its graph, however, the interquantile values don't seem real.

could somebody pls solve it? intrigued..

[physics]

QUESTION to help please:

On a school commitee composed of 8 members, 5 favour that hats should be worn all year, while 3 say only on term 1 and 4 . What is the probability that a randomly chosen subcomitee of 4 will exactly have 3 that will favour all year protection?

probability of wanting all year protection =  5/8
probability of wanting term 1 and 4 protection only=  3/8
    n= 4
    x=3

(  4  )   ( 5/8)^3  (3/8)^1
(  3  )



is this right???
btw answer =   3/7

   

[d0minicz]

The amount of a certain chemical in a type A cell is normally distributed with mean of 10 and a standard deviation of 1, while the amount in a type B cell is normally distributed with a mean of 14 and a standard deviation of 2. To determine whether a cell is a type A or a type B, the amount of chemical in the cell is measured and the cell is classified as a type A if the amount is less than a specified value c, and as being of type B otherwise.

a) If c=12 calculate the probability that a type A cell will be misclassified, and the probability that a type B cell will be misclassified.

b) Find the value of c for which the two probabilities of misclassification are equal.

thank you...

[khalil]

The amount of a certain chemical in a type A cell is normally distributed with mean of 10 and a standard deviation of 1, while the amount in a type B cell is normally distributed with a mean of 14 and a standard deviation of 2. To determine whether a cell is a type A or a type B, the amount of chemical in the cell is measured and the cell is classified as a type A if the amount is less than a specified value c, and as being of type B otherwise.

a) If c=12 calculate the probability that a type A cell will be misclassified, and the probability that a type B cell will be misclassified.

b) Find the value of c for which the two probabilities of misclassification are equal.

thank you...

a) A: normCdf(12,infinity,10,1)=0.0228
   B: normCdf(-infin,12,14,2)=0.1587

b)  Solve for x:  normCdf(x,infin,10,1)= normCdf(-infin,x,14,2)= 11.33= 34/3

[d0minicz]

hey for part b) how did you solve for x ?

[TrueTears]

I think khalil just solved it in the CALC.

[d0minicz]

CAS calc?

[TrueTears]

Yeah.

[/0]

I'm copying this from my exercise book last year, I've forgotten most of this stuff.

b)

[d0minicz]

Coffee and tea are the only drinks available on the farm. If Aidan drank coffee the day before, the probability he will drink coffee the next day is 0.7, and if he drank tea the day before the probability he will drink tea the next day is 0.3. The probability that he does not have enough time to drink anything is 0.2. If this is the case, there is an equal chance that he will choose either tea or coffee the following day.

Aidan drank coffee yesterday.

i) What is the probability he will drink tea today?

ii) What is the probability he will drink tea tomorrow?

thanks

[kamil9876]

i.) 1=Pr(coffee)+Pr(tea)+Pr(nothing)
1=0.7+Pr(tea)+0.2
Pr(tea)=0.1

ii.) Big tree diagram and cbf. Just make sure you have three branches and that the nothing branch has always Probability of 0.2.

[TrueTears]

for ii) I think you can use a markov chain, just a simple matrix.

[d0minicz]

thanks

1. A bucket contains 10 red and 3 green tomatoes. 3 tomatoes are randomly selected.

i) Given that the first tomato he selects is a red tomato, what is the probability that the next two are green tomatoes?

for this one, do i calculate Pr(R) + Pr(G) + Pr (G)
or just Pr(G) + Pr(G) ?

[GerrySly]

I think it's done without replacement so you need to draw a tree diagram really as the probability changes with each selection