A normal distribution has a mean of 50 and a standard deviation of 4. Please i want to determine the value below which 95% of the observations will occur.
Statistics from Cornell's Northeast Regional Climate Center indicate that Ithaca, New York, gets an average of 35.4" of rain each year, with a standard deviation of 4.2". Assume that a Normal model applies. 1) During what percentage of years does Ithaca get more than 40" of rain? 2) Less than how much rain falls in the driest 20% of all years? 3) A Cornell University student is in Ithaca for 4 years. Let represent the mean amount of rain for those 4 years. Describe the sampling distribution model of this sample mean, . 4) What 's the probability that those 4 years average less than 30" of rain?
Assume that the age distribution of the Statistics 101 students has a mean of 23 years and a standard deviation of 3 years. If we randomly sampled 100 students, which of the following statements about the sampling distribution of the sample mean age is incorrect.
A) The sample mean's expected value is the same as the population's mean.
B) The sampling distribution's standard deviation is 3 years.
C) The shape of the sampling distribution is approximately normal.
D) The standard error of the sampling distribution is equal to 0.3 years.
How many strings of three letters can be made from the letters of the English alphabet, if repetition is allowed?