1
WB JEE 2021
MCQ (Single Correct Answer)
+1
-0.25
Change Language
The mean and variance of a binomial distribution are 4 and 2 respectively. Then the probability of exactly two successes is
A
$${7 \over {64}}$$
B
$${{21} \over {128}}$$
C
$${7 \over {32}}$$
D
$${9 \over {32}}$$
2
WB JEE 2021
MCQ (Single Correct Answer)
+1
-0.25
Change Language
Let $${S_n} = {\cot ^{ - 1}}2 + {\cot ^{ - 1}}8 + {\cot ^{ - 1}}18 + {\cot ^{ - 1}}32 + ....$$ to nth term. Then $$\mathop {\lim }\limits_{n \to \infty } {S_n}$$ is
A
$${\pi \over 3}$$
B
$${\pi \over 4}$$
C
$${\pi \over 6}$$
D
$${\pi \over 8}$$
3
WB JEE 2021
MCQ (Single Correct Answer)
+1
-0.25
Change Language
If a > 0, b > 0 then the maximum area of the parallelogram whose three vertices are O(0, 0), A(a cos$$\theta$$, b sin$$\theta$$) and B(a cos$$\theta$$, $$-$$ b sin$$\theta$$) is
A
ab when $$\theta$$ = $${\pi \over 4}$$
B
3ab when $$\theta$$ = $${\pi \over 4}$$
C
ab when $$\theta$$ = $$-$$ $${\pi \over 2}$$
D
2ab
4
WB JEE 2021
MCQ (Single Correct Answer)
+1
-0.25
Change Language
Let A be the fixed point (0, 4) and B be a moving point on X-axis. Let M be the midpoint of AB and let the perpendicular bisector of AB meets the Y-axis at R. The locus of the midpoint P of MR is
A
y + x2 = 2
B
$${x^2} + {(y - 2)^2} = {1 \over 4}$$
C
$${(y - 2)^2} - {x^2} = {1 \over 4}$$
D
$${x^2} + {y^2} = 16$$
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