Answer: 0.345
Step-by-step explanation:
Given : The incomes of families in Newport Harbor are normally distributed with Mean :
and Standard deviation : ![\sigma= $250,000](https://tex.z-dn.net/?f=%5Csigma%3D%20%24250%2C000)
Samples size : n=4
Let x be the random variable that represents the incomes of families in Newport Harbor.
The z-statistic :-
![z=\dfrac{x-\mu}{\dfrac{\sigma}{\sqrt{n}}}](https://tex.z-dn.net/?f=z%3D%5Cdfrac%7Bx-%5Cmu%7D%7B%5Cdfrac%7B%5Csigma%7D%7B%5Csqrt%7Bn%7D%7D%7D)
For x= $800,000
![z=\dfrac{800000-750000}{\dfrac{250000}{\sqrt{4}}}=0.4](https://tex.z-dn.net/?f=z%3D%5Cdfrac%7B800000-750000%7D%7B%5Cdfrac%7B250000%7D%7B%5Csqrt%7B4%7D%7D%7D%3D0.4)
By using the standard normal distribution table , we have
The probability that the average income of these 4 families exceeds $800,000 :-
![P(x>80,000)=P(z>0.4)=1-P(z\leq0.4)\\\\=1-0.6554217=0.3445783\approx0.345](https://tex.z-dn.net/?f=P%28x%3E80%2C000%29%3DP%28z%3E0.4%29%3D1-P%28z%5Cleq0.4%29%5C%5C%5C%5C%3D1-0.6554217%3D0.3445783%5Capprox0.345)
Hence, the probability that the average income of these 4 families exceeds $800,000 =0.345
sqrt (b^2 -4ac ) =sqrt (4-4•3•4) = sqrt (-44) so the parabola does not have real solutions. Answer C)
Answer:
a. (n- x 9) - 5
b. (n + 10) 7
If it's right, give me BRAINLIEST