Thread: Please Help

Please help with several homework questions:

A shop that produces custom kitchen cabinets has two employees, "S" and "C". 95% of "C" work is satisfactory and 10% of "S" work is unsatisfactory. 60% of the shops cabinets are made by "C" (the rest by "S"). Find the following probabilities: (a) an unsatisfactory cabinet was made by "C"; (b) a cabinet is unsatisfactory.


A chapter of union Local 715 has 73 members. In how may different ways can the chapter select a president, a vice-president, a secretary, and a treasurer?



A cellular phone manufacturer randomly selects 5 out of every 50 phone from the assemble line and test them. If at leas 4 of the 5 pass inspection, the batch of 50 is considered acceptable. find the probability that a batch of 50 phones is considered acceptable given the following additional information: (a) the batch of 50 phones contains 2 defectives; (b) the batch of 50 phone containe no defectives (c) the batch of 50 phones contains 3 defectives.


A new factory machine manfactures computer chips in malfunctioning and has a 20% defect rate. If 5 chips are randomly selected from the machine, find the following probabilities. (a) non are defective; (b) less tha 2 are defective.


The insurance industry has found that the probability is .9 that a life insurance applicant will qualify at the regular rates. Find the probability that of the next 10 applicants for life incurance, the following numbers will qualify at the regular rates. (a) exactly 9; (b) at least 9.

Please post these as separate questions. One post with five or more
questions is too much to reply to in one go, and an answer to one or
two will make it look as though the post has been dealt with to other
potential answerers.

Also it might be useful if you could tell us where you are having difficulties,
perhaps by showing us what you have tried and where you are stuck.

RonL

Originally Posted by batman123

A shop that produces custom kitchen cabinets has two employees, "S" and "C". 95% of "C" work is satisfactory and 10% of "S" work is unsatisfactory. 60% of the shops cabinets are made by "C" (the rest by "S"). Find the following probabilities: (a) an unsatisfactory cabinet was made by "C"; (b) a cabinet is unsatisfactory.

C makes 60% of all cabinets of which 95% are satisfactory and 5%
unsatisfactory, so of total production 0.95x0.6 are satisfactory and
made by C and 0.05x0.6 are unsatisfactory and made by C

S makes 40% of all cabinets of which 90% are satisfactory and 10% are
unsatisfactory, so of total production 0.9x0.4 are satisfactory and made by
S, ans 0.1*0.4 are unsatisfactory and made by S.

a) fraction of total production which is unsatisfactory is:

0.1x0.4 + 0.05x0.6 = 0.07

the probability that an unsatisfactory cabinet was made by C is the fraction
of all cabinets that are made by C and unsatisfactory divided by the fraction
of production which is unsatisfactory:

(0.05*0.6)/0.07~0.4286 or ~43%

b) Answer is give above 0.07=7%.

RonL

Originally Posted by batman123

A chapter of union Local 715 has 73 members. In how may different ways can the chapter select a president, a vice-president, a secretary, and a treasurer?

The president can be selected in 73 different ways, having selected the
president the VP can be selected in 72 ways (as there are 72 candidates
available) So for every president there are 72 vice presidents so there are
73 times 72 president VP combinations. Similarly having selected the P and
the VP there are 71 ways of selecting the secretary, thus there are

73x72x71= 373176

P, VP and S combinations.

RonL