1. A sample of 200 snails showed an average speed of 270 cm an hour with a standard deviation of 96. Construct the 99% confidence interval for the true mean speed of snails.

2. You are interested in the proportion of students that do the extra questions you spend hours creating. A sample of 15 students showed that 5 actually did the questions. Construct the 95% confidence interval for the true proportion of students that did extra questions.

3. Good Year wishes to estimate the average life of their Blizzak tires. A sample of 132 tires showed an average life of 123,000 km. with a standard deviation of 19,000. Construct the 90% confidence interval for the true mean life of blizzaks.

4. Air Canada wishes to estimate the proportion of flight that leave Pearson airport on time. A sample of 71 flights showed that 69% left on time. Construct the 99% confidence interval for the true proportion of on time flights.

5. Air Canada wishes to estimate the proportion of on time flights. They wish to be within 2% of on time flights 19 out of 20 times. How large a sample is required to fulfil their requirements.