1. If students picked numbers completely at random from numbers 1 to 20, the proportion of times that the number 7 would be picked is 0.5. When 15 students picked a number "at random" from 1 to 20, 4 of them picked the number 7. What is the sample proportion equal to?

2. The Central research team wanted to estimate the percentage of adults who have laptops in a large city. Six hundred randomly selected residents in this city are surveyed to determine this estimate. Among the 600 adults sampled, 420 responded that they have laptops. Use a 95% confidence level, compute a confidence interval estimate for the true proportion of adult residents of this city who have laptops.