basically, you need to determine which piece of info is sufficient for you to tell whether d=.2 or d=.3. To find it out you may want to know whether h<5 or h>=5, because if h<5 than d=.2, and if h>=5 than d=.3.
if d<1/4 than we know for sure that the value of d to the nearest tenth is .2 (if d<.25 it follows that the hundredth digit of the decimal is less than 5, which, by the way, means that h<5). sufficient
the second condition tells you right away that h<5 and so d=.2.
you round off decimals wrong.
if d=.246 than the value of d to the nearest tenth is .2 but not .3. it is the hunredth digit alone that conditions the value of the tenth. in general, when you round off, the next digit defines the previous.
if d=.1849, for example, the value of d to the nearest hundredth is .18 because the next digit after 8 is 4 and 4<5.