Answer:
Step-by-step explanation:
Hello!
The variable of interest is:
X: number of daily text messages a high school girl sends.
This variable has a population standard deviation of 20 text messages.
A sample of 50 high school girls is taken.
The is no information about the variable distribution, but since the sample is large enough, n ≥ 30, you can apply the Central Limit Theorem and approximate the distribution of the sample mean to normal:
X[bar]≈N(μ;δ²/n)
This way you can use an approximation of the standard normal to calculate the asked probabilities of the sample mean of daily text messages of high school girls:
Z=(X[bar]-μ)/(δ/√n)≈ N(0;1)
a.
P(X[bar]<95) = P(Z<(95-100)/(20/√50))= P(Z<-1.77)= 0.03836
b.
P(95≤X[bar]≤105)= P(X[bar]≤105)-P(X[bar]≤95)
P(Z≤(105-100)/(20/√50))-P(Z≤(95-100)/(20/√50))= P(Z≤1.77)-P(Z≤-1.77)= 0.96164-0.03836= 0.92328
I hope you have a SUPER day!
Answer:

Step-by-step explanation:
Given that

We have slope of linear regression line is

So regression line would be of the form
(since it passes through xbar, y bar)

is the equation of regression line.
Answer:
The graph in the attached figure
Step-by-step explanation:
we have
----> inequality A
The solution of the inequality A is the shaded area below the dashed line 
The slope of the dashed line is negative
The y-intercept of the dashed line is 3
The x-intercept of the dashed line is 9
----> inequality B
The solution of the inequality B is the shaded area above the dashed line 
The slope of the dashed line is positive
The y-intercept of the dashed line is 2
The x-intercept of the dashed line is -2/3
The solution of the system of inequalities is the shaded area between the two dashed lines
see the attached figure
Answer:
A. 560
Step-by-step explanation:
multiply 600 by 0.93 in order to find out what 93% of 600 is.
600 x 0.93 = 558
since 558 isn't one of the options you find which one is closest to it, then divide by 600 in order to see if it's still 93%
a) 560/ 600 = 0.93333 = 93.3%
there's your answer.
but to compare it with the rest of the answer choices:
b) 540 / 600 = 0.9 = 90%
c) 470 / 600 = 0.78333 = 78.3%
d) 490 / 600 = 0.81667 = 81.6%
none of these are in the range of 93, so they're incorrect