Question 1 An executive at a telecommunications company is interested in the relationship between an individual's income and their mobile phone usage. He surveyed 10 mobile-phone users and recorded their annual incomes and time (in minutes) spent each week making national direct calls. The data is presented in sequence according to gross annual income. Individual Annual income (000) National direct calls (minutes) 1 23 69 2 29 95 3 35 118 4 42 136 5 46 125 6 50 138 7 64 166 8 66 184 9 76 170 10 78 225

a. Construct a scatter plot of the data above.

b. Develop a least squares regression line to predict the direct calls in minutes based on annual income.

c. What would be the predicted duration of direct call in minutes for an income of $48000?

d. What is the error value for an income of $76000?

Question 2

The mean score of sixth-formers in Fiji in a national math exam is 75 with a standard deviation of 8.1.

A random sample of 100 students is chosen from one school district in Fiji to see if the mean score in that district is lower than the national average. The mean score of these 100 students is 71.

Does this indicate that the mean score of sixth-formers in that district is significantly higher than 75 at the 5% level of significance?