If $Z+M=88$ and $Z-M=2$,then $M=\ldots \ldots \ldots \ldots . .$

For a given frequency distribution,$A = 200$,$\Sigma f_{i} = 45$,$\Sigma f_{i} u_{i} = -216$ and $c = 10$. Then,mean $\bar{x} = \dots$

For the following data,the median class is $\ldots \ldots \ldots$

Class	$0-10$	$10-20$	$20-30$	$30-40$	$40-50$
Frequency	$12$	$18$	$20$	$17$	$13$

Find the mean of the following frequency distribution:

Class	$10-20$	$20-30$	$30-40$	$40-50$	$50-60$	$60-70$
Frequency	$2$	$10$	$40$	$25$	$13$	$10$

(in $.7$)

In a maths test taken by $40$ students,the average score of $30$ boys is $16$ and the average score of $10$ girls is $12$. Which of the following gives the average score of the whole class?

Midpoint (Midvalue) of the class $15-30$ is ........