$$y=A e^x+B e^{-2 x}$$ satisfies which of the following differential equations?
If $$N_A, N_B$$ and $$N_C$$ are the number of significant figures in $$A=0.001204 \mathrm{~m}, B=43120000 \mathrm{~m}$$ and $$C=1.200 \mathrm{~m}$$ respectively, then
A car covers a distance at speed of $$60 \mathrm{~km} \mathrm{~h}^{-1}$$. It returns and comes back to the original point moving at a speed of $$v$$. If the average speed for the round trip is $$48 \mathrm{~kmh}^{-1}$$, then the magnitude of $$v$$ is
A car travels with a speed of $$40 \mathrm{~km} \mathrm{~h}^{-1}$$. Rain drops are falling at a constant speed vertically. The traces of the rain on the side windows of the car make an angle of $$30^{\circ}$$ with the vertical. The magnitude of the velocity of the rain with respect to the car is