Abox contains 13 transistors, 4 of which are defective. if 4 are selected at random, find the probability that a. all are defective. b. none are defective.

(a) The probability that all are defective is .

(b) The probability that all are defective is .

Step-by-step explanation:

It is given that a box contains 13 transistors, 4 of which are defective.

Total number of transistors = 13

Total number of defective transistors = 4

Total number of non-defective transistors = 13 - 4 = 9

Number of selected transistors = 4

Total possible ways to select 4 transistors from 13 transistors is

(a)

We need to find the probability that none are defective.

It means all 4 transistors are from defective transistors.

The probability that all are defective is

Therefore the probability that all are defective is .

(b)

We need to find the probability that none are defective.

It means all 4 transistors are from non-defective transistors.

The probability that none are defective is

Therefore the probability that none are defective is .

< coa = 150 ( given)

as ba and bc are tangents

so oc and oa is perpendicular to cb and ab respectively because in circle normal passes through centre

so in quadrilateral oabc

< coa + < oab + < ocb + < abc = 360

150 +90+90 + < abc = 360

330 + < abc = 360

< abc = 360 -330 = 30

so < abc = 30

⭐dhruv⭐

the anwser is d) 75°

step-by-step explanation: