$4)$ A$)$What is the equilibrium cant on a $2\mathrm{.}5\backslash$deg curve on a broad gauge for several trains running with certain speeds as given below:

i$)20$ trains at a speed of $70$ km$.$p$.$h

ii$)15$ trains at a speed of $60$ km$.$p$.$h

iii$)10$ trains at a speed of $80$ km$.$p$.$h

Also, find the speed for which superelevation is to be maintained.

B$)$ If a $6\backslash$deg curve tack diverges from a main curve of $4\backslash$deg in an opposite direction in the layout of a B$.$G$.$ yard, calculate the superelevation and the speed on the branch line, if the maximum speed permitted on the main line is $50$ km$.$p$.$h$.($Given cant deficiency $=7\mathrm{.}6$ cm