My answer to Q2 is incorrect.
I now realize that I have fallen down the chasm of mixing up TV set and
coloured TV set!
I need to rethink the problem .....
..... Andre
On 7 February 2011 22:06, Andre Francis <[log in to unmask]> wrote:
> Q1. If 1 = defective.
>
> 1a p(11) = 2/4x1/3 = 1/6
>
> 1b p(101 or 011) = 2/4x2/3x1/2x2 = 1/3
>
> 1c 1- (1a + 1b) = 1 - (1/6 + 1/3) = 1/2
>
>
>
> Q2 The information given yields (for a population of 400): n(U and T)=57;
> n(NotU and T)=120; n(U and NotT)=3 where U = 'upper class' and T =
> TV-owning. The above can be seen to give: a 6/17 b 177/400 c 19/59
>
>
>
> Q3 The problem is essentially p(> 25 connections / minute). If we consider
> a connection as the start of a call and a 'rush hour' as precisely 1 hour,
> then the probability can be calculated using a Poisson distribution, mean
> 500/60 = 8.33 ..... which yields probability zero (Am I missing something?)
> What if there were 26 calls at 1-second intervals, each lasting for less
> than 1 second? Would this overtax the board? ... and so on!
>
>
> I hope this is of some use
>
>
> Andre Francis
>
>
>
> On 7 February 2011 15:36, marina garcia <[log in to unmask]>wrote:
>
>> hi allstat,
>>
>> pls kindly help me with these probability problems:
>>
>> 1. Two defective tubes got mixed up with two good ones. The tubes
>> are tested one by one until both defectives are found.
>>
>> a)What is the probability that both defectives have been found by
>> the second test?
>> b)What is the probability that three tests are required?
>> c)What is the probability that four tests are required?
>>
>> 2. In a certain city, 15% of the households are classified as being
>> of the “upper class”, according to socio-economic criteria. In
>> addition, it is known that 95% of upper-class households own
>> colored television sets. It is known that 30% of households that
>> are not of upper-class status own a TV set. If a sample household
>> is to be selected for interview such that all the households of
>> the city are equally likely to be selected, find the probability
>> that
>> a) it does not belong to the upper class but owns a colored
>> television set.
>> b) it owns a colored television set.
>> c) it belongs to the upper class, given that it owns a TV set.
>>
>> 3. A telephone switchboard handles 500 calls, on an average, during a
>> rush hour. The board can make a maximum of 25 connections per
>> minute. Evaluate the probability that the board will be overtaxed
>> during any given minute.
>>
>>
>> pls pm me the solutions or links to problems similar to the given
>> above, if possible, with solutions...
>>
>> your help is highly appreciated...thanks a lot
>>
>> marina garcia
>> uplb, philippines
>>
>>
>>
>>
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