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:
The number of roots for equation 
is 4 .
Step-by-step explanation:
Here, the given function polynomial is :
The Fundamental Theorem of Algebra says that a polynomial of degree n will have exactly n roots (counting multiplicity).
Now here, the degree if the polynomial is 4 (highest power of variable x).
So, according to the Fundamental Theorem, the given polynomial can have AT MOST 4 roots, counting Multiplicity.
Hence, the number of roots for equation is 4 .
Subtract 2.1 from both sides:
Add 1.4y to both sides:
Of course, we can rewrite this as
Divide both sides by 1.4
