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lutik1710 [3]
3 years ago
7

You measure the lifetime of a random sample of 25 rats that are exposed to 10 Sv of radiation (the equivalent of 1000 REM), for

which the LD 100 is 14 days. The sample mean is = 13.8 days. Suppose that the lifetimes for this level of exposure follow a Normal distribution, with unknown mean μ and standard deviation σ = 0.75 day. What is the 95% confidence interval for μ based on these data?
Mathematics
1 answer:
Slav-nsk [51]3 years ago
4 0

Answer:

CI 95%(μ)= [13.506 ; 14.094]

Step-by-step explanation:

The confidence interval (CI) formula is:

CI (1-alpha) (μ)= mean+- [(Z(alpha/2))* σ/sqrt(n)]

alpha= is the proportion of the distribution tails that are outside the confidence interval. In this case, 5% because 100-90%

Z(5%/2)= is the critical value of the standardized normal distribution. In this case is 1.96

σ= standard deviation. In this case 0.75 day

mean= 13.8 days

n= number of observations . In this case 25

Then, the confidence interval (90%) is:

CI 95%(μ)= 13.8+- [1.96*(0.75/sqrt(25)]

CI 95%(μ)= 13.8+- [1.96*(0.75/5) ]

CI 95%(μ)= 13.8+- (0.294)

CI 95%(μ)= [13.8-0.294 ; 13.8+0.294]

CI 95%(μ)= [13.506 ; 14.094]

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2x + y = 9<br> x = y - 3
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Answer:

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Step-by-step explanation:

Steps:

I will solve your system by substitution.

x=y−3;2x+y=9

Step: Solve x = y − 3 for x:

Step: Substitute y − 3 for x in 2x + y = 9:

2x+y=9

2(y−3)+y=9

3y−6=9(Simplify both sides of the equation)

3y−6+6=9+6(Add 6 to both sides)

3y=15

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y=5

Step: Substitute 5 for y in x = y − 3 :

x=y−3

x=5−3

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Answer:

x=2 and y=5

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3 years ago
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Step-by-step explanation:

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