Math Is Fun Forum

A study of 98 investment advisors asked them to predict the value of a "penny" stock a week ahead.  The correlation between the values predicted and the actual value was .20.  Was this evidence that they could predict penny stock performance?

a) state the null and alternative hypotheses about the correlation

b) calculate the test statistic

c) perform the test at significance level of .05

You are testing the null hypothesis that there is no linear relationship between two variables, X and Y.  From your sample of n=8, you determine that b1=+4.5 and Sb1=1.5.

d) what is the value of tstat?

e) at the .05 level of significance, what are the critical values?

f) based on your answers to (c) and (d), what statistical decision should you make?

The 68-95-99.7 rule simply states that 68.26% of values will lie within one standard deviation of the mean. 95.44% of values will lie within 2 standard deviations and 99.73% within 3 standard deviations of the mean. Describe an example using an assumed mean and standard deviation to illustrate the ranges of their normal distribution.

I read the chapter twice and all question on the test that went like the one below I failed. Where should I start?

Suppose it is observed that, on average, 35 people are admitted to the intensive care unit of a particular hospital every week. Let the random variable X represent the number of people admitted to this intensive care unit on any particular day.

a) What is the distribution of X?
b) What is the probability that the number of people admitted to this intensive care unit on a particular day is exactly 5?
c) What is the probability that the number of people admitted to this intensive care unit on a particular day is exactly 2?
d) What is the probability that the number of people admitted to this intensive care unit on a particular day is less than 2?