Answer:
Step-by-step explanation:
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:
6 dollars per hour
Step-by-step explanation:
We can set up and solve an equation to answer this question. For this problem, let x stand for the amount he earned per hour. The equation that represents this situation is 3.2x + 4.3x = 45. The first term represents monday and the second represents tuesday. When these add up they should equal 45 because that is the total amount he made. To find his pay per hour, solve for x.
First, combine the like terms
Next, divide both sides by 7.5
Each book costs $15. 90 divided by 6 is 15 which is also 90 over 6.