1
BITSAT 2021
MCQ (Single Correct Answer)
+3
-1

Box I contains 5 red and 2 blue balls, while box II contains 2 red and 6 blue balls. A fair coin is tossed. If it turns up head, a ball is drawn from box I, else a ball is drawn from box II. The probability ball drawn is from box I, if it is blue, is

A
$${{27} \over {56}}$$
B
$${{8} \over {29}}$$
C
$${{21} \over {29}}$$
D
$${{29} \over {56}}$$
2
BITSAT 2021
MCQ (Single Correct Answer)
+3
-1

For a random variable X, E(X) = 3 and E(X2) = 11. The variable of X is :

A
8
B
5
C
2
D
1
3
BITSAT 2021
MCQ (Single Correct Answer)
+3
-1

The sum of 10 items is 12 and the sum of their squares is 18, then the standard deviation will be

A
$$-$$3/5
B
6/5
C
4/5
D
3/5
4
BITSAT 2021
MCQ (Single Correct Answer)
+3
-1

The height of the chimney when it is found that on walking towards it 50 m in the horizontal line through its base, the angle of elevation of its top changes from 30$$^\circ$$ to 60$$^\circ$$ is :

A
25 m
B
25$$\sqrt2$$ m
C
25$$\sqrt3$$ m
D
None of these
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