Answer: 0.4
-----------------------------------------
Explanation:
P(q) = 0.2
P(r) = unknown
P(q and r) = 0.08
Since events q and r are independent, this means we can use the formula
P(q and r) = P(q)*P(r)
Plug in the given info and isolate P(r)
P(q and r) = P(q)*P(r)
0.08 = 0.2*P(r)
0.2*P(r) = 0.08
P(r) = 0.08/0.2 <<-- divide both sides by 0.2
P(r) = 0.4
