Respuesta :
Answer:
a) 0.789, this is the complement of the probability of no repeat offenders; b) 0.411; c) 0.033; d) μ = 1.429; e) σ = 9.58
Step-by-step explanation:
For part a,
The probability that no parolees are repeat offenders is 0.211. Â This means the probability of at least one is a repeat offender is the complement of this event. Â To find this probability, subtract from 1:
1-0.211 = 0.789.
For part b,
To find the probability that 2 or more are repeat offenders, add together the probability that 2, 3, 4 or 5 parolees are repeat offenders:
0.216+0.162+0.032+0.001 = 0.411.
For part c,
To find the probability that 4 or more are repeat offenders, add together the probabilities that 4 or 5 parolees are repeat offenders:
0.032+0.001 = 0.033.
For part d,
To find the mean, we multiply each number of parolees by their probability and add them together:
0(0.211)+1(0.378)+2(0.216)+3(0.162)+4(0.032)+5(0.001)
= 0 + 0.378 + 0.432 + 0.486 + 0.128 + 0.005 = 1.429
For part e,
To find the mean, we first subtract each number of parolees and the mean to find the amount of deviation. Â We then square it and multiply it by its probability. Â Then we add these values together and find the square root.
First the differences between each value and the mean:
0-1.429 = -1.429;
1-1.429 = -0.429;
2-1.429 = 0.571;
3-1.429 = 1.571;
4-1.429 = 2.571;
5-1.429 = 3.571
Next the differences squared:
(-1.429)^2 = 2.0420
(-0.429)^2 = 0.1840
(0.571)^2 = 0.3260
(1.571)^2 = 2.4680
(2.571)^2 = 6.6100
(3.571)^2 = 12.7520
Next the squares multiplied by the probabilities:
0(2.0420) = 0
1(0.1840) = 0.1840
2(0.3260) = 0.652
3(2.4680) = 7.404
4(6.6100) = 26.44
5(12.7520) = 63.76
Next the sum of these products:
0+0.1840+0.652+0.7404+26.44+63.76 = 91.7764
Lastly the square root:
√(91.7764) = 9.58
Probabilities are used to determine the outcomes of events.
- The probability that one or more are repeat offenders is 0.789
- The probability that two or more are repeat offenders is 0.411
- The probability that four or more are repeat offenders is 0.033
- The standard deviation of repeat offenders is 1.093
- The expected number of repeat offenders is 1.429
The table is given as:
[tex]\left[\begin{array}{ccccccc}x &0 &1 &2 &3 &4 &5 &P(x) &0.211 &0.378 &0.216& 0.162 &0.032 &0.001\end{array}\right][/tex]
(a) Probability that one or more are repeat offenders
This is represented as: [tex]P(x \ge 1)[/tex]
Using the complement rule, we have:
[tex]P(x \ge 1) = 1 - P(x = 0)[/tex]
So, we have:
[tex]P(x \ge 1) = 1 - 0.211[/tex]
[tex]P(x \ge 1) = 0.789[/tex]
The probability that one or more are repeat offenders is 0.789
(b) Probability that two or more are repeat offenders
This is represented as: [tex]P(x \ge 2)[/tex]
Using the complement rule, we have:
[tex]P(x \ge 2) = 1 - P(x = 0) - P(x = 1)[/tex]
So, we have:
[tex]P(x \ge 2) = 1 - 0.211 - 0.378[/tex]
[tex]P(x \ge 2) = 0.411[/tex]
The probability that two or more are repeat offenders is 0.411
(c) Probability that four or more are repeat offenders
This is represented as: [tex]P(x \ge 4)[/tex]
So, we have:
[tex]P(x \ge 4) = P(x = 4) + P(x = 5)[/tex]
[tex]P(x \ge 4) = 0.032 + 0.001[/tex]
[tex]P(x \ge 4) = 0.033[/tex]
The probability that four or more are repeat offenders is 0.033
(d) The expected number of repeat offenders
This is calculated as:
[tex]\mu = \sum x \times P(x)[/tex]
So, we have:
[tex]\mu = 0 \times 0.211+ 1\times 0.378 + 2 \times 0.216 + 3 \times 0.162 + 4 \times 0.032 + 5 \times 0.001[/tex]
[tex]\mu = 1.429[/tex]
The expected number of repeat offenders is 1.429
(e) The standard deviation
This is calculated as:
[tex]\sigma= \sqrt{\sum (x^2 \times P(x)) - \mu^2}[/tex]
[tex]\sum (x^2 \times P(x))[/tex] is calculated as:
[tex]\sum (x^2 \times P(x)) = 0^2 \times 0.211+ 1^2 \times 0.378 + 2^2 \times 0.216 + 3^2 \times 0.162 + 4^2 \times 0.032 + 5^2 \times 0.001[/tex]
[tex]\sum (x^2 \times P(x)) = 3.237[/tex]
So, we have:
[tex]\sigma= \sqrt{\sum (x^2 \times P(x)) - \mu^2}[/tex]
[tex]\sigma = \sqrt{3.237 - 1.429^2}[/tex]
[tex]\sigma = \sqrt{1.194959}[/tex]
[tex]\sigma = 1.093[/tex]
The standard deviation of repeat offenders is 1.093
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