How Do We Calculate Expected Defects in Quality Control Samples?

[Calculator14]

Homework Statement

The number of defects in a sample of 20 parts is recorded for quality control purposes; over the last year the number of defects and their occurrence rate has been : 0 defects, 82%; 1 defect, 13%; 2 defects, 4%; 3 defects, 1%. Find the expected number of defects in the next sample of 20 parts.

Homework Equations

(work shown below)

The Attempt at a Solution

1*.13+2*.04+3*.01=.24
20*.24=4.8 the expected number of defects in the next sample of 20 parts.

 

[tiny-tim]

Hi Calculator14!

1*.13+2*.04+3*.01=.24
20*.24=4.8 the expected number of defects in the next sample of 20 parts.

hmm … you don't know when to stop, do you?

How can the expected number be between 4 and 5 when the given probabilities only go up to 3 ??

What do you think the 0.24 is ? ​

 

[Calculator14]

OHHHHHHHH! So I think I went a little too far with this, haha! My apologies tiny-tim, thank you for pointing out my mistake! I believe my answer should be .24??

 

[tiny-tim]

he he!

yes ​