Students in a school were surveyed about their study habits. Forty-two percent of students said they study on weeknights and weekends, 47% said they studied on weekends, and 65% said they study either on weeknights or weekends. If you were to pick one student at random, what is the probability that he or she studies on a weeknight?

0.6 = 60% probability that he or she studies on a weeknight.

Step-by-step explanation:

We solve this question treating these events as Venn probabilities.

I am going to say that:

Probability A: Probability of a student studying on weeknights.

Probability B: Probability of a student studying on weekends.

Forty-two percent of students said they study on weeknights and weekends

This means that

47% said they studied on weekends

This means that

65% said they study either on weeknights or weekends.

This is

If you were to pick one student at random, what is the probability that he or she studies on a weeknight?

This is P(A), and the equation used is:

Considering the values we have:

0.6 = 60% probability that he or she studies on a weeknight.

logv3(x+2)=1

rewrite in exponential form:

logb(x) = y is equal to b^y =x

b = 3, y = 1

now solve for x:

3^1 = x+2)

x = 3-2

x = 1

see the picture for the graph.

(b) 240

step-by-step explanation:

first, we use the pythagorean formula using the given side lengths to find x. then we use x to find the side lengths. then we add the side lengths to find the perimeter.

pythagorean theorem formula:

a^2 + b^2 = c^2

(x - 20)^2 + (x - 40)^2 = x^2

x^2 - 40x + 400 + x^2 - 80x + 1600 = x^2

x^2 -120x + 2000 = 0

(x - 100)(x - 20) = 0

x - 100 = 0 or x - 20 = 0

x = 100 or x = 20

we see that the solution x = 20 must be discarded because it will give a negative side length and a side length of 0. the only valid solution is x = 100.

perimeter = sum of the lengths of the sides

perimeter = x + x - 20 + x - 40

perimeter = 3x - 60

replace x with 100.

perimeter = 3(100) - 60

perimeter = 300 - 60

perimeter = 240