Question

a cog company produces 20 cogs a day, 4 of which are defective. Find the probability of selecting 4 cogs from the 20 produced where none are defective?

Answer 1

Probability of selecting a non-detective cog = 16/20

Required Probability = 16/20 * 15/19 * 14/18* 13/17 = 364/969

= 0.3756 or 37.56 % answer

=

Answer 2

`\bf\implies \text {Required Probbaility = }(364)/(969)`

Explanation:

Number of cogs produced by the company = 20

Number of cogs which are defective = 4

no. of cogs which are not defective = 20 - 4

= 16

Now, we need to find the probability of selecting 4 cogs which are not defective

`\text{Required Probability = }(16)/(20)* (15)/(19)* (14)/(18)*(13 )/(17)\\\\\implies\text{Required Probability = }(43680)/(116280)\\\\\bf\implies \text {Required Probability = }(364)/(969)`