PQR is a triangular park with PQ = PR = 200 m. A T.V. tower stands at the mid-point of QR. If the angles of elevation of the top of the tower at P, Q and R are respectively 45$$^\circ $$, 30$$^\circ $$ and 30$$^\circ $$, then the height of the tower (in m) is :

The Boolean expression

$$ \sim \left( {p \vee q} \right) \vee \left( { \sim p \wedge q} \right)$$ is equvalent to :

The density of a material in the shape of a cube is determined by measuring three sides of the cube and its mass. If the relative errors in measuring the mass and length are respectively 1.5% and 1%, the maximum error in determining the density is:

All the graphs below are intended to represent the same motion. One of them does it incorrectly. Pick it up.