What does the y-intercept and what does it indicate

Given the following sampling distribution of one mean with a sample size 49, from a normally distributed population, find the population standard deviation, o.79828588912497

At a pizza shop 70% of the customers order a pizza 25% of the customers order a salad and 15% of the customers order both a pizza and a salad if s customer is chosen at random what is the probability that he or she orders either a pizza or a salad

How can you find the magnitude of a vector, v = < x, y > , where the horizontal change is x and the vertical change is y?