Answer:
C.
Step-by-step explanation:
Hello!
Given the variable:
X: childhood asthma prevalence
With mean μ= 2.22%
and standard deviation σ= 1.39%
You have to calculate the probability of the sample average of childhood asthma prevalence in a sample of n= 30 cities is greater than 2.5%
We don't know the distribution of the variable, but remember that thanks to the central limit theorem, since the n ≥ 30, we can approximate the sampling distribution to normal:
X[bar]≈N(μ;σ²/n)
And use the standard normal distribution to calculate the asked probability:
P(X[bar]>2.5)= 1 - P(X≤2.5)
Calculate the Z value for the given X[bar] value:
![Z= \frac{X[bar]-Mu}{\frac{Sigma}{\sqrt{n} } } = \frac{2.5-2.22}{\frac{1.39}{\sqrt{30} } }= 1.10](https://tex.z-dn.net/?f=Z%3D%20%5Cfrac%7BX%5Bbar%5D-Mu%7D%7B%5Cfrac%7BSigma%7D%7B%5Csqrt%7Bn%7D%20%7D%20%7D%20%3D%20%5Cfrac%7B2.5-2.22%7D%7B%5Cfrac%7B1.39%7D%7B%5Csqrt%7B30%7D%20%7D%20%7D%3D%201.10)
Using the Z-tables you have to look for the value of
P(Z≤1.10)= 0.86433
1 - 0.86433= 0.13567
Then P(X[bar]>2.5)= 1 - P(X≤2.5)= 1 - P(Z≤1.10)= 1 - 0.86433= 0.13567
13.567% of the 30 cities will have a mean childhood asthma prevalence greater than 2.5%
I hope this helps!
N = 15
24÷2=12+3=15
........
check
15 -3 = 12
12 × 2 = 24
Answer:
2.64
Step-by-step explanation:
x² + 6= 13
x² = 13-6
x²= 7
x = square root of 7
x = 2.64