Probability

[d0minicz]

hey thanks for that , but im still confused with how to solve for the answer
i got up to the probability function, but still not sure what to do ...

[kamil9876]

well you can solve Pr=0.1 with calculator. But your answer will be like 3.something. So the real answer is 4 since you can only select an integer number of chocolates and it is the least integer that satisfies Pr>0.1

[d0minicz]

oh okay so the book's answer of 7 is wrong right ?

[kamil9876]

actually 7 is the right answer. Just checked now. when n=6, Pr=0.0818, when n=7 Pr=0.1147. Hence n=7.

I think I mistakenly thought the question wanted 0.01 when I looked at it earlier. 

[d0minicz]

Monique is practising goaling for netball. She knows from past experience that her chances of making any one shot is about 70%. Her coach has asked her to keep practising until she scores 50 goals. How many shots would she need to attempt to ensure that the probability of making at least 50 shots is more than 0.99?

dunno how to do this one on the calc ... help please x]

thanks !!

[d0minicz]

If the random variable X has the probability density function given by :
a) Find the interquartile grange of X giving answer to 3 decimal places

thx

[TrueTears]

If the random variable X has the probability density function given by :

What's your question?

[d0minicz]

yeh quesiton fixed =]

[d0minicz]

Ill do it again properly lol

1. If the random variable X has the probability density function given by :
Find the interquartile range of X giving answer to 3 decimal places.


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.


thank you ~!

[d0minicz]

anyone =]

[physics]

I have a porbability problem that i want help withhh please

Radial tyres last atleast 55000km. They test 8 tyres. If 75% or more of the 8 tyres he tests lasts atleast 55000km, he will buy the tyres. If, 90% of the tyres last atleast 55000km, what probability iis that the tyre dealer will purchase tyres?

[monokekie]

I have a porbability problem that i want help withhh please

Radial tyres last atleast 55000km. They test 8 tyres. If 75% or more of the 8 tyres he tests lasts atleast 55000km, he will buy the tyres. If, 90% of the tyres last atleast 55000km, what probability iis that the tyre dealer will purchase tyres?

this is a bionomial probability distribution.

there are only two outcomes, either last for "at least 55000" or "less than 55000"

8 tyres are tested. so the n value should be 8. n=8
"75% or more" indicated the number of tyres that "last atleast 55000" is 6 or more (75% x 8 = 6)  x≥6

the condition, "that 90% will last atleast 55000" provides us with the probablity of success, P=0.9

now, open your book to the formula of the binomial probability distribution, substitute the values in bold into the formula.

do you get the right answer?

edit: i got 0.9619 ≈ 0.962

[d0minicz]

lol any ideas on my questions monokekie ?

[physics]

I have a porbability problem that i want help withhh please

Radial tyres last atleast 55000km. They test 8 tyres. If 75% or more of the 8 tyres he tests lasts atleast 55000km, he will buy the tyres. If, 90% of the tyres last atleast 55000km, what probability iis that the tyre dealer will purchase tyres?

this is a bionomial probability distribution.

there are only two outcomes, either last for "at least 55000" or "less than 55000"

8 tyres are tested. so the n value should be 8. n=8
"75% or more" indicated the number of tyres that "last atleast 55000" is 6 or more (75% x 8 = 6)  x≥6

the condition, "that 90% will last atleast 55000" provides us with the probablity of success, P=0.9

now, open your book to the formula of the binomial probability distribution, substitute the values in bold into the formula.

do you get the right answer?

edit: i got 0.9619 ≈ 0.962

YYAYAYAYA thanks!!!

[monokekie]

1. If the random variable X has the probability density function given by :
Find the interquartile range of X giving answer to 3 decimal places.

sorry, i overlooked your post lol

we know that interquantile range is the difference between the 75th percentile and the 25th percentile.

since you have already drawn a graph, which appears to be symmetrical to the y axis, you could conclude that the 25th percentile of this hybrid function would be the 50 percentile, of the right hand side only , of the right hand side graph. . （ie,area under the right hand-side curve, bounded by the 25th percentile range, equals to 0.5）

so, i would antidifferentiate this equation first, make the upper boundary 0, and let the lower boundary be an unknown, a. then solve for a by making the antiderivative equal to 0.5.

the value a is your 25th percentile. i got -IN(0.5)

since it is symmetrical, the value for the 75th percentile would be of the same magnitude, which is IN(0.5).

add the two values up. IN(0.5)x2 =1.38629≈ 1.386 (ignore any negative value since we are only interested in the difference between them)

is my solution understandable? please ask if its too messy because i am ESL...