Solve the following problems (1 - 6)

1.9. The passenger train of 10 carriages. In how many ways you can place the cars, making this train?

2.9. In Stock Repair Shop 10 of piston rings, three of them recovered. Determine the probability that among the four taken at random two rings will be restored?

3.9. In the coming assembly parts with three CNC machines. The first machine gives 20%, second - 30, the third - 50% similar parts entering the assembly. Find the probability that taken at random from three parts: a) with three different machines; b) three and a third machine; c) a third two of the machine.

4.9. Five boxes with 30 balls in each contains 5 red balls, six other boxes with 20 balls in each - 4 red spheres. Find the probability that: a) taken at random from a box at random take the ball will be red; b) taken at random red ball contained in one of the first five boxes.

5.9. Probability of hitting a target for the arrow is on average 80%. The shooter made 6 shots on target. Find the probability that the target was hit by: a) five times; b) at least five times; c) not more than five times.

6.9. The probability of a violation of the standard at stamping karbolitovyh rings is 0.3. Find the probability that the number of defective workpieces 800 rings lies between 225 and 250.

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