1
JEE Main 2024 (Online) 9th April Evening Shift
+4
-1

If the variance of the frequency distribution

$$x$$ $$c$$ $$2c$$ $$3c$$ $$4c$$ $$5c$$ $$6c$$
$$f$$ 2 1 1 1 1 1

is 160, then the value of $$c\in N$$ is

A
5
B
8
C
6
D
7
2
JEE Main 2024 (Online) 9th April Morning Shift
+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
3
JEE Main 2024 (Online) 6th April Morning Shift
+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
4
JEE Main 2024 (Online) 4th April Evening Shift
+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
$$\frac{173}{27}$$
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