Statistics

#1
These are heights and weights for five randomly-selected adults. Units are centimeters and kilograms, respectively.
height 183 172 190 167 193
weight 91 83 99 83 104

a. Find a linear equation which predicts weight as a function of height. Be sure to define your variables clearly.
b. According to your equation, what should a 160 centimeter adult weigh?
c. Explain why the prediction in part (b) is likely to be close to correct, or explain why it probably is not.
 
#2
Normal Distribution

Assume that IQ scores are normally distributed, with standard deviation 15. Some randomly selected IQ scores for adults from one country are 94, 114, 104, 97, 133, 81, 120, 109, 111, and 116. Use this information to construct a 95%-confidence interval for the mean IQ in that country.
 
#3
statistics help needed

A randomly-selected group of 21 people were each asked to play a new video game. Below are the numbers of points they scored. The scored are grouped according to the age, in years, of the players.
below 20 {23, 51, 42, 36, 29, 44, 53}
20 to 40 {42, 33, 20, 45, 55, 22, 30}
above 40 {31, 25, 24, 36, 27, 37, 22}
Is it 95%-certain that the three mean scores of all potential players below 20, all potential players between 20 and 40, and all potential players above 40 are not the same? Explain how you proved your answer.