Solve the following problems (1 - 6)
1.28. Of the group of students of Faculty of Civil Engineering in 16 people formed two construction brigades 10 and 6 people. In how many ways you can create these teams?
2.28. The chess tournament involved 20 people, which are distributed by lot in two groups of 10 people. Find the probability that the two strongest chess players will play in different groups.
3.28. Computing Center, which should produce a continuous processing of incoming information has two computing devices. It is known that the probability of failure for a time T for each of them is 0.2. Find the probability of failure-free operation in the time T a) of each device; 6) at least one device; c) a single device.
4.28. At the site where the bolts are made, the first machine produces 25% of the second - 35, the third - 40% of all products. The products of each of the machines marriage is respectively 5, 4 and 2%. Find the probability that: a) a bolt taken at random - defective; b) randomly taken defective bolt is made on the third machine.
5.28. The probability of hitting the target is 0.3. Simultaneously, six bombs dropped. Find the probability that the target is: a) four bombs; b) at least four bombs; c) not more than four bombs.
6.28. The germination of seeds of this plant is 0.9. Find the probability that out of 900 planted germinated seed number will be entered into between 790 and 830.