Problem with a Hal Varian Question from chapter 5 Remember our friend Ralph Rigid from Chapter 3? His favorite
diner, Food for Thought, has adopted the following policy to reduce the
crowds at lunch time: if you show up for lunch t hours before or after
12 noon, you get to deduct t dollars from your bill. (This holds for any
fraction of an hour as well.)

(a) Use blue ink to show Ralph's budget set. On this graph, the horizontal
axis measures the time of day that he eats lunch, and the vertical axis
measures the amount of money that he will have to spend on things other
than lunch. Assume that he has 20 total to spend and that lunch at
noon costs 10. (Hint: How much money would he have left if he ate at
noon? at 1 P.M.? at 11 A.M.?)

(b) Recall that Ralph's preferred lunch time is 12 noon, but that he is
willing to eat at another time if the food is sufficiently cheap. Draw
some red indifference curves for Ralph that would be consistent with his
choosing to eat at 11 A.M.

The answer is given as 

My question is, shouldnt the graph be perfectly parabolic? with both tangents at Time = 11 and 1.
Shouldn't eating at 11 be exactly as preferable to eating at 1?

Thanks for the help.
I think the answer to your question is that it would be a matter of Ralph's preferences. Perhaps he is indifferent to eating at 11:00 am or 1:00 pm, as you suggest. But he might have non-parabolic preferences (for reasons unspecified), and both this situation and the one you describe are consistent with his eating at 11:00 am, so the answer provided is a correct solution to the question asked. Perhaps the particular indifference curves drawn are a way to avoid multiple solutions (the author might have thought it simpler).

I'm going exclusively off the information in your post though, so I'm assuming that we do not know if Ralph has any preferences over time independent of how it implicitly affects the price he pays.