Which one of the following measures of central tendency is the most suitable for evaluating the intelligence of students based on their marks?

If for some $x \in R$,the frequency distribution of the marks obtained by $20$ students in a test is:
Marks: $2, 3, 5, 7$
Frequency: $(x+1)^2, 2x-5, x^2-3x, x$
Then the mean of the marks is:

Find the median for the following distribution:

Class	Frequency
$10-20$	$180$
$20-30$	$82$
$30-40$	$34$
$40-50$	$180$
$50-60$	$136$
$60-70$	$23$
$70-80$	$50$

The $A.M.$ of a $50$ set of numbers is $38$. If two numbers of the set,namely $55$ and $45$,are discarded,the $A.M.$ of the remaining set of numbers is

If the mean of $3, 4, x, 7, 10$ is $6$,then the value of $x$ is

Which of the following,in the case of discrete data,is not equal to the median?