1000 worms weight .5 kg, and each worm can eat half its body weight per day. Each student produces 25 g of food scrap and there are 30 students. What is the minimum amount of worms they need?

Aclassroom is made up of 11 boys and 14 girls. the teacher has four main classroom responsibilities that she wants to hand out to four different students (one for each of the four students). if the teacher chooses 4 of the students at random, then what is the probability that the four students chosen to complete the responsibilities will be all boys?