Question

Ten percent of the items produced by a machine are defective. out of 15 items chosen at random, what is the probability that less than 3 items will be defective?

Answer 1

Quality controla process that evaluates output relative to a standard and takes corrective action when output doesn't meet standardsinspectionappraisal of goods and services
-necessary to physically examine some of the goodsacceptance samplingDo existing shipments meet predetermined standards?process controlIs the process stable? Future Output Acceptable?inspectionHow Much to Inspect/How Often
At What points should inspection occur 
Centralized vs. On-site
Attributes vs. Variableswhere to inspect in the processRaw materials and purchased parts
Finished products
Before a costly operation
Before an irreversible process
Before a covering processcentralized labspecial equipment, more favorable testing atmosphere, etcon sitequicker decisions, avoidance of other extraneous factors,etc.attributescharacteristics which are present or not present; they are counted
EX: is the top of the bottle cracked or not?variablescharacteristics which are present in varying degrees; they are measured
EX: diameter of a washer boltacceptance samplingForm of inspection applied to lots or batches of items before or after a process, to judge conformance with predetermined standardssampling plansPlans that specify lot size, sample size, number of samples, and acceptance/rejection criteriasingle planone random sample is drawn from the lot and every item in sample is examined.
< c defects; Accept
> c defects; Rejectdouble plantake a second sample if first is inconclusive.
< c1 defects; Accept
> c2 defects; Reject
in second sample:
< c3 defects; Accept
> c3 defects; Rejectmultiple plansame logic as double-plan except additional samples are drawn until you clearly fall into either the acceptance or rejection category
-Choosing a plan depends on cost and time. cost of analysis vs. cost of drawing sampleoperating characteristics curveIt is generally not optimal to inspect all items so we have to sample some %. The problem is that you can't discriminate perfectly between good and bad lots without 100% inspection.
-An important feature is how well it discriminates between lots of high quality and lots of low quality.
-shows the probability that use of the sampling plan will result in lots with various fraction defectives being acceptedacceptance quality level (AQL)the percentage level of defects at which consumers are willing to accept lots as "good" (1-2%)lot tolerance percent defective (LTPD)the upper limit on the percentage of defects that a consumer is willing to acceptconsumers risk (beta)the probability that a lot containing defectives exceeding the LTPD will be accepted