(a) Solution: 1 Mark
      Name: 1 Mark
(b) Concept: 1 Mark
     Steps: 1 Mark
(a) No of parts Arush has eaten = 4
Total no of parts = 6
So fraction of parts he has eaten = $\frac{4}{6}=\frac{2}{3}$
Fraction of watermelon remaining = $1-\frac{2}{3}=\frac{3-2}{3}=\frac{1}{3}$
The fractions $\frac{2}{3}$ and $\frac{1}{3}$ are called proper fractions.
(b) Total time of Suman’s study =  $5\frac{2}{3}=\frac{17}{3}$ hours
Time devoted by her for Science and Mathematics =  $2\frac{4}{5}=\frac{14}{5}$ hours
Thus, time devoted by her for other subjects = $\frac{17}{3}-\frac{14}{5}$
= $\frac{17\times 5}{15}-\frac{14\times 3}{15}$
= $\frac{43}{15}$
= $2\frac{13}{15}$