Statistics questions... help please?

1. a manufacturer of boots plans to conduct an experiment to compare a new method of waterproofing to the current method. the appeareance of the boots is not changed by either method. the company recruits 100 volunteers in Seattle, where it rains frequently, to wear the boots as they normally would for 6 months.at the end of the months, the boots will be returned to he company to be evaluated for water damage. is there a double blind in this problem?





2. you are considering purchasing one of two comparable photocopy machines, A or B. machine A is $10,000 and machine B is $10,500. this department replaces photocopy machines every 3 years. the repair contract for machine A costs 50 per month and covers an unlimited number of repairs.The contract for machine B costs 200 per repair. based on past performance, the distribution of the # of repairs needed over any 1 year period for machine B is as followed


# of repairs:0,1,2,3


probability:.5,.25,.15,.1


which one would you choose and why

Statistics questions... help please?
1. if the person handing out the boots the volunteers does not know if which boots were treated with which water proofing method then both the administrator and the volunteer are "blind" to knowing the method and you have a double blind.





if the person handing out the boots knows which boots have had which treatment and only the volunteers don't know then this is single blind.





2.





First we will find the expected number of repairs for machine B in one year





For any discrete random variable the expectation is:





E(X) = μ = ∑x * P(X = x)





E(number of repairs) =


0 * 0.5 + 1 * 0.25 + 2 * 0.15 + 3 * 0.1


= 0.85





the expected cost of repairs per year for machine B is:





0.85 * $200 = $175 per year





for the three year period we would expect to have a repair cost of 3 * 175 = $525 for machine B





The total expected cost of machine B is thus


10500 + 525 = $ 11025





the total expected cost of machine A is


10000 + 50 * 36 = $ 11800





Machine B is expected to be cheaper in the long run.
Reply:1. I thinkkk that the words either moethod is a double blind... because they were using only 1 method so either method means more than 1 method so it would not make sense





2. i would choose machine B because even if it costs more, we dont have to pay monthly repair fees even if we dont have repairs and it would be cheaper with B because the probability of no repairs per year is more than a repair.



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