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:
First one is 15.Second one is 3
Step-by-step explanation:
1 inch:10 meters 150÷10:15 26÷2:13 6÷2:3
Answer:
y = 3/2x - 7
Step-by-step explanation:
slope-intercept: y = mx + b
m = slope (3/2)
b = y-intercept (-7)
when put together, the equation is y = 3/2x - 7.
To solve this equation, start by noticing that you want to find t when P is 75%, or 0.75. Plug in 0.75 for P. Please see the attached screenshot for a step-by-step. The correct answer is 29.496 days.
EDIT 2: I actually was correct! You check the answer by substituting 29.496 for t in the original equation set equal to 0.75. It is 0.75. I had forgotten the negative sign when I checked.
