13-15. A die is tossed twice. Getting 'a number greater than 4' is considered a success. Find the mean and variance of the probability distribution of the number of successes. Cuna de arear

Statisticsghu

Children being exposed to unsafe levels of lead exposure is thought to be to an environmental factor increasing the chance of a child being diagnosed with ADHD. During the 1990s about 0.3% of children were exposed to unsafe levels of lead (usually from lead pipes). 3. If we let X = the number of children in our study with exposure to unsafe levels of lead we can use the binomial distribution to model the probability distribution of X. Explain why using the definition of Binomial from your notes. (Recall we randomly selected the 425 children and the probability a child is exposed is 0.3%. 4. The researchers found that 5 children in the study had unsafe levels of lead in their blood, Find the probability that in a random sample of 425 children we find at least 5 that have exposure to unsafe levels of lead. 5. Is it unusual to find at least 5 that have exposure to unsafe levels of lead? Explain showing work.

Is the expected value (mean) of the probability distribution of a random variable always one of the possible values of x from the distribution ? Explain