# Recent questions tagged statistics

1
For two data sets, each of size $5$, the variances are given to be $4$ and $5$ and the corresponding means are given to be $2$ and $4$ respectively. The variance of the combined data is? $11/2$ $6$ $13/2$ $5/2$
2
A class of first year B.tech students is composed of four batches A, B, C and D, each consisting of $30$ students. It is found that the sessional marks of students in Engineering Drawing in batch C have a mean of $6.6$ and standard deviation of $2.3$. The mean and the standard deviation of ... class. Due to this, the marks of a student in batch C are changed from $8.5$ to $6.0$ $7.0$ $8.0$ $9.0$
1 vote
3
The following sequence of numbers is arranged in increasing order: $1,x,x,x,y,y,9,16,18$. Given that the mean and median are equal, and are also equal to twice the mode, the value of $y$ is $5$ $6$ $7$ $8$
1 vote
4
The second moment of a Poisson-distributed random variable is 2. The mean of the variable is .... My question on solving we get 2 values of lamda(ie mean) .One is -2 and the other is 1 .So which one to choose?
1 vote
5
For what value of 'k' (in terms of $X_{i}$'s) following functions will attain their minimum value $\rightarrow$ $F_{1}(k)$ = $\sum_{i=0}^{n} \left | X_{i} - k \right |$ $F_{2}(k)$ = $\sum_{i=0}^{n}\left ( X_{i} - k \right )^{2}$ If possible, please provide some valid proof for supporting your answer ?
6
the harmonic mean of two positive integers p and q is 3, given that [ (6p+1)/(7q-4) ] <(p/q), what could be the value of q? a)q<=4 b)q>9 c)q<8 d)q>=13
1 vote
7
In a company with $100$ employees, $45$ earn $Rs. 20,000$ per month, $25$ earn $Rs. 30000$, $20$ earn $Rs. 40000$, $8$ earn $Rs. 60000$, and $2$ earn $Rs. 150,000$. The median of the salaries is $Rs. 20,000$ $Rs. 30,000$ $Rs. 32,300$ $Rs. 40,000$
8
Students taking an exam are divided into two groups, P and Q such that each group has the same number of students. The performance of each of the students in a test was evaluated out of $200$ marks. It was observed that the mean of group P was $105$, while that of ... Most students of group Q scored marks in a narrower range than students in group P. The median of the marks of group P is $100$.
9
10
What is the median of data if its mode is 15 and the mean is 30? 30 25 22.5 27.5
11
The arithmetic mean of attendance of 49 students of class A is 40% and that of 53 students of class B is 35%. Then the percentage of arithmetic mean of attendance of class A and B is 27.2% 50.25% 51.13% 37.4%
12
If the mean of a normal frequency distribution of 1000 items is 25 and its standard deviation is 2.5, then its maximum ordinate is $\frac{1000}{\sqrt{2 \pi} } e^{-25}$ $\frac{1000}{\sqrt{2 \pi} }$ $\frac{1000}{\sqrt{2 \pi} } e^{-2.5}$ $\frac{400}{\sqrt{2 \pi} }$
13
The statistics of runs scored in a series by four batsmen are provided in the following table. Who is the most consistent batsman of these four? ... $K$ $L$ $M$ $N$
14
The arithmetic mean of five different natural numbers is $12$. The largest possible value among the numbers is $12$ $40$ $50$ $60$
1 vote
15
what is positively skewed ,symmetric and negatively skewed distribution?
Let $A$ and $B$ be non-empty disjoint sets of real numbers. Suppose that the average of the numbers in the first set is $\mu_{A}$ and the average of the numbers in the second set is $\mu_{B}$; let the corresponding variances be $v_{A}$ and $v_{B}$ respectively. If the average of the elements in $A \cup B$ ... $p.v_{A}+ (1 - p). v_{B} + (\mu_{A}- \mu_{B})^{2}$
Q) Let $x$ be normal variable with mean $8$ and standard deviation $4$ then $p(X\leq5)$ is A). Greater than zero but less than $0.5$ B). Greater than $0.75$ C). Greater than $0.5$ but less than $1$ D). Equal to $0.5$
Which of the following assertions are CORRECT? P: Adding $7$ to each entry in a list adds $7$ to the mean of the list Q: Adding $7$ to each entry in a list adds $7$ to the standard deviation of the list R: Doubling each entry in a list doubles the mean of the list S: Doubling each entry in a list leaves the standard deviation of the list unchanged $P$, $Q$ $Q$, $R$ $P$, $R$ $R$, $S$