Answer:
11 : Look at the numbers after 4, 4.23 has a two directly after it's 4, in comparison to 4.135 which has a 1 after its 4. This means that no many how many numbers are after 4.1, it will always be less than 4.23.
12 : .33, .331, .332, .333, .334, .335, .336, .337, .338, .339, .34 Although realistically you could get smaller by going like this : .3301, .3302, etc.
13 : Thirteen is correct! Great job!
14: 0.5 is less than 6/10, I'll provide you with a hint for your number line. .5 = 5/10
15 : 4, 3, 2 would all be potential digits.
16 : Ana's score was higher than Marcias.
15.500-15.050 = the difference between the two scores.