The graph below shows the numbers of cans of juice purchase each hour from a school's vending machines in one day. on the x- axis of the graph, 7 means the time for 7: 00 to 8: 00 and so on.

This is how I would answer these questions:
the high is at around lunch time, and the lows are at the beginning and end of each school day. This makes sense because students are more likely to buy a juice to go with lunch and less likely to need a juice early morning or early evening. At 5:00, the sale is higher than at 3 and 4, probably because students have after-school sports activities at around 5:00 pm.
 It doesn't make sense to connect all the dots because they are too scattered. Time and number of cans do not form an visible positive or a negative correlation. 

Just for your reference.

The principal, real, root of: 50−−√2=7.071067817.07106781−7.0710678150 is not a perfect square