Thread: Tree Diagram Help

Hi hows it going guys. I have some problem with tree diagram.

A manufacturer of metal bolts uses an X-ray scanner to reject bolts which have defects. In a review of the scanner’s reliability, 750 bolts were checked by the scanner and then by an accurate human inspector. The table shows the number of bolts accepted or rejected by the scanner and whether the bolts were, in fact, defective or OK.
In this question, the following notation should be used.
A: the casting was accepted by the scanner
D: the casting was defective Scanner


(a)Draw a tree diagram and label its branches to show the sample space of this problem.

(b)On the basis of these results, calculate the probability correct to 4 decimal places, that a randomly selected bolt
(i)is defective and is accepted by the scanner
(ii)is accepted by the scanner
(iii)will be accepted by the scanner if it is defective

many thanks

Answer to (a)

Originally Posted by omrkwlh

(b)On the basis of these results, calculate the probability correct to 4 decimal places, that a randomly selected bolt
(i)is defective and is accepted by the scanner
(ii)is accepted by the scanner
(iii)will be accepted by the scanner if it is defective

many thanks

i) 12/750 =

ii) 734/750 =

iii) 12/18 =

Originally Posted by Glaysher

Answer to (a)

Corrected diagram in attachment

Originally Posted by CaptainBlack

Corrected diagram in attachment

Stupid typo. Thanks

those 2 events A and D are they considered as mutually exclusive or independent?

Originally Posted by omrkwlh

those 2 events A and D are they considered as mutually exclusive or independent?

Mutually exclusive means they can't happen together ie probability of A and D happening together is zero

Independent means the probability of A and D happening together is the same as the probability of A happening multiplied by the probability of D happening

err still dont get it mate