The average of marks obtained by 120 students in a certain examination is 35. If the average marks of passed students is 39 and that of the failed students is 15, what is the number of students who passed in the examination?

If the variables $x$ and $z$ are so related that $z = ax + b$ for each where $a$ and $b$ are constant, then $\bar{z} = a\bar{x} + b$.

If the mean of the following distribution is $6$, then the value of $P$ is: $ \begin{array}{|c|c|c|c|c|c|} \hline $X$ & 2 & 4 & 6 & 10 & $P+5$ \\ \hline $F$ & 3 & 2 & 3 & 1 & 2 \\ \hline \end{array} $

There are $n$ numbers. When 50 is subtracted from each of these number the sum of the numbers so obtained is $-10$. When 46 is subtracted from each of the original $n$ numbers, then the sum of numbers so obtained is 70. What is the mean of the original $n$ numbers?

Which measure is suitable for open-end classification?

$50^{th}$ Percentile is equal to

Find the median of the following. Class: 0-10, 10-20, 20-30, 30-40, 40-50; Freq: 2, 3, 4, 5, 6