Answer
a) 2.3
b) 2.4
c) 2.3
d) 2.4
Work Step by Step
a) you are given 2.34, in order to bring that down you must round the four down since it is closer to zero than to 10 so it is 2..3
b) you are given 2.35, in this case, you round up because although 5 is in the middle, you always round it up 2.4
c) you are given 2.349, to solve this you can ignore the 9 after the four since it is not relevant and since the four is lower than 5 it stays at 2.3
d) you are given 2.359, in this case, you can just see that the second decimal is 5 and just round up to 2.4