Question 1 :
On Thursday, $20$ of the $25$ students in a chemistry class took a test and their average (arithmetic mean) was $80$. On Friday, the other $5$ students took the test and their average (arithmetic mean) was $90.$ What was the average for the entire class?
Question 2 :
The mean of $1, 2, 3,\cdots \left ( n+1 \right )is\ \dfrac{6n}{11}$, then the value of n equals
Question 3 :
The sum $\displaystyle \sum _{ r=1 }^{ 10 }{ \left( { r }^{ 2 }+1 \right) \times \left( r\ ! \right) }$ is equal to:
Question 4 :
The following observations have been arranged in ascending order. If the median of the data is $78$, find the value of $x$.<br/>$44, 47, 63, 65, x + 13, 87, 93, 99, 110$.
Question 5 :
If the mean of $x+2$, $2x+3$, $3x+4$, $4x+5$ is $x+2$, then $x$ is equal to
Question 9 :
The mean of 30, 32, 24, 34, 26, 28, 30, 35, 33, 25 is 29.7<br/>If true then enter $1$ and if false then enter $0$<br/>
Question 11 :
The mean of $\displaystyle x_{1},x_{2}$...$\displaystyle x_{50}$ is M, if every $\displaystyle x_{i},=1,2$...50 is replaced by $\displaystyle x_{i}/50$ then the mean is
Question 13 :
If 16 observations are arranged in ascending order, then median is :
Question 14 :
The following data has been arranged in ascending order. If their median is $63$, find the value of $ x\ : $<br>$34,37,53,55,x,x+ 2,77,83,89 $ and $100$<br>
Question 15 :
If the median of $\displaystyle \frac{x}{5}$ $\displaystyle x$ $\displaystyle \frac{x}{4}$ $\displaystyle \frac{x}{2}$ and $\displaystyle \frac{x}{3}$ $\displaystyle \left ( where\, x> 0 \right )$ is $8$ then the value of $x$ would be
Question 16 :
The average age of $8$ persons in a committee is increased by $2$ years when two men aged $35$ years and $45$ years are substituted by two women. What is the average age of these two women ?
Question 17 :
A set F, which contains the elements $4, 5, 11, 13, 16, 18,$ and x. If both the median and average(arithmetic mean) of Set F equal $11$, what must be the value of x?
Question 18 :
The mean marks of $25$ students of X A in board examination is $67$ and that of $30$ students of X B is $75$. Find the mean of the marks of all the $55$ students correct to one decimal place.<br/>
Question 19 :
The mean of $20$ observations is $12.5$. By error, one observation was noted as $-15$ instead of $15$. Then the correct mean is __________.
Question 20 :
Find the average of all the number between $6$  and $34$  which are divisible by  $5$.
Question 23 :
The mean weight of a class of $34$ students is $6.5$kg. If the weight of the teacher is included, the mean rises by $500$g. Then the weight of the teacher is __________.
Question 24 :
The wickets taken by a bowler in a one day cricket match are 4, 5, 6, 3, 4, 0, 3, 2, 3, 5. The mode of the data is ...............
Question 25 :
Wheat was purchases in the fist year at Rs 9 / kg in second year at Rs 10/kg and in the third year at Rs 11/kg ,if each year Rs 990 were spend in purchasing wheat the average cost of wheat during the three year is nearly 
Question 26 :
The mean of the cubes of the first n natural numbers is
Question 28 :
The mean of the following data is :<br/>$45, 35, 20, 30, 15, 25, 40$<br/>
Question 29 :
Find the mean of the following data :<br/>$30, 32, 24, 34. 26, 28, 30. 35, 33, 25$
Question 30 :
The following observations have been arranged in ascending order. If the median of the data is $78$ find the value of $x\: $.<br/>$44,47,63,65, x+13, 87,93, 99,110.$<br/>
Question 31 :
Means of a set of 60 values is 23 ,if 4 is added to each these values the the new mean is
Question 32 :
The mean of five numbers is $18$. If one number is excluded, then their mean is $16$, the excluded number is ___________.
Question 33 :
If the arithmetic mean of $5, 7, 9, x$ is $9$, then the value of $x$ is 
Question 34 :
The mean of $ x, x+2, x+4, x+6 $ and $ x+8$ is $11.$ find the mean of the first three observations.<br>
Question 36 :
The daily sale of kerosene (in litres) in a ration shop for six days is as follows : $75$, $120$, $12$, $50$, $70.5$ and $140.5$ The average daily sale is
Question 37 :
The _____ of a set of data is the middlemost number in the set.<br>
Question 38 :
The captain of a cricket team of $11$ members is $26$ years old and the wicket keeper is $3$ years older. If the ages of these two are excluded, the average age of the remaining players is one year less than the average age of the whole team. What is the average age of the team?
Question 39 :
Emmy did a survey of how many games each of $20$ friends owned, and got the following data: $5, 7, 12, 13, 4, 6, 8, 12, 9, 16, 13, 12, 5, 13, 7, 17, 3, 9, 12, 14.$ Find the mean.<br/>
Question 41 :
The average of $15$ results is $50$. If the average of first $8$ results is $48$ and that of the last $8$ is $53$, find the eigth result.<br/>
Question 42 :
The mean weight of $150$ students in a certain class is$ 60$ kg. The mean weight of boys in the class is $70$ kg. and that of the girls is$ 55 $kg., the ratio of boys and girls respectively is 
Question 45 :
The average age of 6 students is 11 years. If two more students of age 14 and 16 years join, their average will become
Question 46 :
The average of $11$ results is $50$. If the average of the first six results is $49$ and that of the last six is $52$, then the sixth result is _____________.
Question 47 :
The following data has been arranged in ascending order. If their median is $63$, find the value of $x$.$34, 37, 53, 55, x, x+ 2, 77, 83, 89$ and $100$.
Question 49 :
The sum of $12$ observations is $600$ then their mean is _____
Question 50 :
The median $31, 16,19, 25, 14, 13,12, 4, 28, 45$ is 
