03077491076
contestada

Among 10 laptop computers, five are good and five have defects. Unaware of this, a customer buys 6 laptops. (a) What is the probability of exactly 2 defective laptops among them? (b) Given that at least 2 purchased laptops are defective, what is the probability that exactly 2 are defective.

Respuesta :

Use combinations, The total outcomes for this is 10C6 = (10!/(6!(10-6)!)=210
The number of outcomes with support question "a" are 5C2*5C4= 10*5=50 (2 from 2 defective so there are 4 not defective)
The probability is 50/210= 0.238 = 23.8%
Part b: as they say "at least" that means greater than 2, so you need the probability for 1 defective + 2 defective, for 1 defective you solve 5C1*5C5/10C6= 0.024. Add the probabilities for 1 and 2 defective 0.238+0.024=0.262 = 26.2% probability at least 2 laptops defectives.


In the given question by adding the probability for 1 & 2 defective computers to get a total of [tex]23.81+2.38 =26.19\%[/tex] chance of at least two defective laptops.

Probability calculation:

For point a:

When 5 out of 10 are faulty.

Let X represent the number of defectives among some of the 6 people chosen at random. For parameters [tex](N=10, k=5 ,n=6)[/tex], X follows the Hypergeometric Distribution.

We want to find the probability that [tex]X = 2[/tex].

[tex]\text{P(2 are d\1efective)} = \frac{ \text{(of ways of selecting 4 of 5 non-d\1efective and 2 of 5 de fective)}}{\text{( total of ways of selecting 6 from 10)}}[/tex]

[tex]\to \frac{\binom{5}{4}\binom{5}{2}}{\binom{10}{6}}= \frac{5 \times 10}{210} =\frac{5}{21}= 0.238095 \approx 0.2381[/tex]

Calculating the probability percentage:

[tex]\to 0.2381\times 100\\\\\to 23.81\%[/tex]

For point b:

In this question there we use the "at least" which implies that is greater than 2, we required the probability for 1 defective + 2 defective, for 1 defective that is solved as:

[tex]\to ^5 C_1\times \frac{^5C_5}{^{10} C_6}\\\\\to \frac{5!}{1! \times 5-1!} \times \frac{ \frac{5!}{5! \times 5-5!} }{\frac{10!}{6! \times 10-6!}}\\ \\ \to \frac{5!}{1! \times 4!} \times \frac{ \frac{5!}{5! \times 0!} }{\frac{10!}{6! \times 4!}}\\ \\[/tex]

[tex]\to \frac{5\times 4!}{1 \times 4!} \times \frac{ \frac{5!}{5! \times 1} }{\frac{10\times 9 \times 8 \times 7 \times 6! }{6! \times 4 \times 3 \times 2 \times 1}}\\\\\to 5 \times \frac{ 1 }{10\times 3 \times 7 }\\\\\to \frac{ 1 }{2\times 3 \times 7 }\\\\\to \frac{ 1 }{ 42}\\\\ \to 0.023[/tex]

Calculating the probability:

[tex]\to 0.023 \times 100\\\\\to 2.38\%[/tex]

Add the probability for 1 & 2 defective computers to get a total of [tex]23.81+2.38 =26.19\%[/tex] chance of at least two defective laptops.

Find out more information about the probability here:

brainly.com/question/15409496

Otras preguntas