Ms. Tucker travels through two intersections with traffic lights as she drives to the market. The traffic lights operate independently. The probability that both lights will be red when she reaches them is .22. the probability that the first light will be red and the second light will not be red is .33. what is the probability that the second light will be red when she reaches it?
5 answers
0.55
that is incorrect, according to college board.
.4
The probability of two independent events occurring in succession is the product of the two events' independent probabilities. .22 = that product. Because we know the probability of the first being red and the second not being red (.33), we know the probability of the first light being red: .22 + .33. That comprises all the possible ways the first light can be red.
From there, just divide .22 by .55 in order to get .4. Tough problem because they phrased it ambiguously.
The probability of two independent events occurring in succession is the product of the two events' independent probabilities. .22 = that product. Because we know the probability of the first being red and the second not being red (.33), we know the probability of the first light being red: .22 + .33. That comprises all the possible ways the first light can be red.
From there, just divide .22 by .55 in order to get .4. Tough problem because they phrased it ambiguously.
.40
You need a tree diagram. Make the branch Red Red =.22, and Red NRed=.33 and assign variables on the starting branches, then solve for the variable values.
1 answer