Solve the following problems (1 - 6)

1.24. How many permutations can be made from the letters of the word "rocket" that they all begin with "p" letter?

2.24. The boy forgot last two digits of the telephone number a classmate and scored them at random, I only remember that these numbers are odd and different. Find the probability that it is correct.

3.24. In box 50% of the parts produced at the plant number 1, 20% - at the plant number 2, and 30% - at the plant number 3. Randomly taken three parts. Find the probability that: a) all three parts - a plant number 1; b) two parts - a plant number 1; c) all three parts - with different plants.

4.24. The unit includes a first type of radio tubes 6 and 10 the second. The warranty period is usually withstand 80% of tubes of the first type and 90% of the second type. Find the probability that: a) taken at random vacuum tube stand the warranty period; b) vacuum tube, endured the warranty period, the first type.

5.24. The probability of hitting the target each of the seven shots equals 0.8. Find the probability of hitting the target: a) two shots; b) at least one shot; c) at least three shots.

6.24. The probability that the product - top quality, equal to 0.5. Find the probability that the number of the 400 articles of the highest quality products will be from 194 to 208.

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