If the mean of the following distribution is 27, then the value of p is :

1. 6

2. 7

3. 9

4. 11

The mean of 5 numbers is 27. If one of the numbers be excluded, their mean is 25. The excluded number is :

1. 25

2. 26

3. 28

4. 35

The mean of n observations is $\bar x$. If the first observation is increased by 1, second by 2 and so on, then the new mean is :

1. $\bar x$ + n

2. $\bar x$ + $\Big(\dfrac{n}{2}\Big)$

3. $\bar x$ + $\Big(\dfrac{n + 1}{2}\Big)$

4. $\bar x$ + $\Big(\dfrac{n − 1}{2}\Big)$

In the formula $\bar x = a + \Big(\dfrac{\sum f$i di}{\sum f_i}\Big) for finding the mean of grouped data, d_is are deviations from a, of :

1. lower limits of the classes

2. upper limits of the classes

3. mid-points of the classes

4. frequencies of the class marks