# probability

A random experiment of tossing a die twice is performed. Random variable X on this
sample space is defined to be the sum of two numbers turning up on the toss. Find the
discrete probability distribution for the random variable X and compute the corresponding
mean and standard deviation.

1. Damon

36 possibilities
number of times sum
1 * 2 = 2
2 * 3 = 6
3 * 4 = 12
4 * 5 = 20
5 * 6 = 30
6 * 7 = 42
5 * 8 = 40
4 * 9 = 36
3 * 10= 30
2 * 11= 22
1 * 12= 12
-----------
36 and 252
mean = 252/36 = 7

2. Paul

A dictionary contains 80,000 words, of which a certain student knows 30,000. If 100 of the 80,000 words are selected at random from the dictionary without replacement, find the probability:the student knows exactly 40 of the 100 words

## Similar Questions

1. ### math

let the random variable x denote the number of girls in a five-child family. if the probability of a female birth is .5 find the probability of 0,1,2,3,4, and 5 girls in a five-child family. construct the binomial distribution and …
2. ### Statistics

Suppose that the probability distribution of a random variable x can be described by the formula P(x) = x/15 For each of the values x = 1, 2, 3, 4, and 5. For examples, then, p(x=2) = p(2) = 2/15 a Write out the probability distribution …
3. ### Statistics and Probability

A computer supply house receives a large shipment of blank CDs each week. Past experience has shown that the number of flaws per CD can be described by the following probability distribution, where the random variable X represents …
4. ### Statistics and Probability

Suppose you took 1000 random samples of size 200 from the Poisson distribution with u = 5 and computed a 90% confidence interval for each sample. Approximate the probability that at least 920 of these intervals would contain the mean …
5. ### statistics

two dices are tossed once. let the random variable be t he sum of the up faces on the dice. A). find and graph the probability distribution of the random variable. and b) calculate the mean (or expectation) of this distribution
6. ### stor

Suppose that you flip a fair coin (P(H)=P(T)=1 2 ) three times and you record if it landed on heads, H, or tails, T. (a) What is the sample space of this experiment?
7. ### Probability

For each of the following statements, determine whether it is true (meaning, always true) or false (meaning, not always true). Here, we assume all random variables are discrete, and that all expectations are well-defined and finite. …
8. ### Math

An ordinary (fair) die is a cube with the numbers 1 through 6 on the sides (represented by painted spots). Imagine that such a die is rolled twice in succession and that the face values of the two rolls are added together. This sum …
9. ### Statistics/probability

The random variable X has a binomial distribution with the probability of a success being 0.2 and the number of independent trials is 15. The random variable xbar is the mean of a random sample of 100 values of X. Find P(xbar<3.15).
10. ### Math

For the discrete random variable X, the probability distribution is given by P(X=x)= kx x=1,2,3,4,5 =k(10-x) x=6,7,8,9 Find the value of the constant k E(X) I am lost , it is the bonus question in my homework on random variables so …

More Similar Questions