1
JEE Main 2024 (Online) 9th April Morning Shift
MCQ (Single Correct Answer)
+4
-1

The frequency distribution of the age of students in a class of 40 students is given below.

Age 15 16 17 18 19 20
No of Students 5 8 5 12 $$x$$ $$y$$

If the mean deviation about the median is 1.25, then $$4x+5y$$ is equal to :

A
43
B
46
C
44
D
47
2
JEE Main 2024 (Online) 6th April Morning Shift
MCQ (Single Correct Answer)
+4
-1

The mean and standard deviation of 20 observations are found to be 10 and 2 , respectively. On rechecking, it was found that an observation by mistake was taken 8 instead of 12. The correct standard deviation is

A
1.94
B
$$\sqrt{3.96}$$
C
$$\sqrt{3.86}$$
D
1.8
3
JEE Main 2024 (Online) 4th April Evening Shift
MCQ (Single Correct Answer)
+4
-1

If the mean of the following probability distribution of a radam variable $$\mathrm{X}$$ :

$$\mathrm{X}$$ 0 2 4 6 8
$$\mathrm{P(X)}$$ $$a$$ $$2a$$ $$a+b$$ $$2b$$ $$3b$$

is $$\frac{46}{9}$$, then the variance of the distribution is

A
$$\frac{581}{81}$$
B
$$\frac{566}{81}$$
C
$$\frac{151}{27}$$
D
$$\frac{173}{27}$$
4
JEE Main 2024 (Online) 4th April Morning Shift
MCQ (Single Correct Answer)
+4
-1

Let $$\alpha, \beta \in \mathbf{R}$$. Let the mean and the variance of 6 observations $$-3,4,7,-6, \alpha, \beta$$ be 2 and 23, respectively. The mean deviation about the mean of these 6 observations is :

A
$$\frac{16}{3}$$
B
$$\frac{11}{3}$$
C
$$\frac{14}{3}$$
D
$$\frac{13}{3}$$
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