Statistics and Probability Answers

An association of city mayor conducted a study to determine the average number of times a family went to buy necesarries in a week.They found out that the mean is 4 times in a week

A recent study showed that the modern working person experiences an average of 2.1 hours per day of distractions (phone calls, e-mails, impromptu visits, etc.). A random sample of 50 workers for a large corporation found that these workers were distracted an average of 1.8 hours per day and the population standard deviation was 20 minutes. Estimate the true mean population distraction time with 90% confidence, and compare your answer to the results of the study.

List all the possible samples and the corresponding mean

. An employee’s weekly income in a certain online job follows a normal distribution with a mean of PHP1,000 and a standard deviation of PHP100. What is the z value for the income of:

Don, a canteen owner claims that the average meal cost of his usual customer is 190 pesos. In order to test his claim , don took a random sample of 25 customers and found out that the meal cost is 210 with a standard deviation of 30 pesos. Test the hypothesis at 0.01 level of significance

Q life time of led follow exponential distribution with mean life of 5000 burning hours. if one such LED is selected at random from a big lot, what is the probability that it will last for 

1. at least 4000 hours 

2. almost 10000 hours

Also state the standard deviation of the life time distribution. Given e raised to -0.8 is 0.4493 and e raised to -2 is 0.1353

A group of students got the following scores in an achievement test:9,12,15,18,21 and 24 . consider the sample of size 3 that can be drawn from this population. Construct a sampling distribution of the resulting means and find the probability