The vector field $$\,F = x\widehat i - y\widehat j\,\,$$ (where $$\widehat i$$ and $$\widehat j$$ are unit vectors) is

A box contains $$10$$ screws, $$3$$ of which are defective. Two screws are drawn at random with replacement. The probability that none of the two screws is defective will be

If $$L$$ denotes the laplace transform of a function, $$L\left\{ {\sin \,\,at} \right\}$$ will be equal to

Maximum strains in an extreme fibre in concrete and in the tension reinforcement (Fe-$$415$$ grade and $${E_s} = 200\,\,kN/m{m^2}$$) in a balanced section at limit state of flexure are respectively