Solve the following problems (1 - 6)

1.1. On the farm work of the three teams recovered one person. It is known that in the first team of 15 people, the second - 12 the third - 10 people. Determine the number of possible groups of 3 persons, if it is known that each worker can be sent to agricultural work.

2.1. I made up the word "song" Of the five letters of the alphabet split. A child who can not read, scattered letters, and then collected in a random order. Find the probability that he again turned the word "song".

3.1. In the TV studio three television cameras. Probability that the currently enabled camera, are respectively 0.9; 0.8; 0.7. Find the probability that currently includes: a) two chambers; b) no more than one camera; c) three cameras.

4.1. 20% with the use of devices mounted micromodule, the others - with the use of integrated circuits. Reliability of the device with micromodules - 0.9, integrated circuits - 0.8. Find: a) the probability of reliable operation of the device taken at random; b) the likelihood that the device - a micromodule, if he was OK.

5.1. The germination of seeds of some plants is 80%. Find the probability that the sown seeds of 6 rises: a) three; b) at least three; at four.

6.1. The probability of occurrence of events in each of the independent trials is 0.25. Find the probability that the event occurs 50 times in 243 trials.

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