You ask a neighbor to water a sickly plant while you are on vacation. without water the plant will die with probability 0.7. with water it will die with probability 0.6. you are 86 % certain the neighbor will remember to water the plant.

So the plant without water has a 0.6 chance of living. with water has a 0.7, so a 0.1 increase of chance if the neighbor comes.

the probability that the neighbor to water the plant is of 0.86.

Then the probability of the plant to live is 0.6 + 0.1*0.86 = 0.686.

So the plant have a 68.6% probability to live

50 min

step-by-step explanation:

they will be decreasing both their times in half

60 / 2 = 30

40/2 = 20

30 + 20 = 50