An automobile driver travels from a plain to a hill station $120$km away at an average speed of $30$ km per hour.He then makes the return trip at an average speed of $25$ km per hour. He covers another $120$km on the plain at an averge speed of $50$km per hour. His average speed ( in km/hr) over the entire distance of $360$km will be

When tested, the lives (in $\mathrm{hours}$) of $5$ bulbs were noted as follows: $1357, 1090, 1666, 1494, 1623$
The mean deviations (in $\mathrm{hours}$) from their mean is

Following are the marks obtained by $9$ students in a mathematics test: $50, 69, 20, 33, 53, 39, 40, 65, 59$. The mean deviation from the median is

If the mean of the distribution is $2.6$, then the value of $y$ is

The following data gives the distribution of height of students:

The median of the distribution is