A study considered risk factors for HIV infection among intravenous drug users [11]. It found that 40% of users who had ≤ 100 injections per month (light users) and 55% of users who had > 100 injections per month (heavy users) were HIV positive. 4.54 What is the probability that exactly 3 of 5 light users are HIV positive?

0.576

Step-by-step explanation:

For light users, given the Probability is X<100 is:

p = P(X < =100)= 40% = 0.4

q = 1 - 0.4 = 0.6

Given n=5 and x=3, we use Bernoulli probabilty distribution

P(X=x) = nCx ×(p)^x ×(q)^n-x

P(X=3) = 5C3 × (0.4)³ × (0.6)²

= 10 × 0.16 × 0.36

= 0.576

to plot points   for x just start at the origin (middle) and go to the left however many times it say(if the number is a positive) if the number is a negative then go right however many times it says if it is 0 go nowhere

now keep you pencil there and go up however many times it says on y(if it is positive) if it is negative then go down however many times it says. if it says 0 go nowhere.

you have just plotted a point! now when you finish plotting all of them connect them with a ruler

plot each point as (-3, 7), (0,4), (3,1), (8,-4)   in the parenthesis on the left of the comma is x and the right is y.