1
JEE Main 2022 (Online) 24th June Evening Shift
Numerical
+4
-1
Out of Syllabus
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In an examination, there are 10 true-false type questions. Out of 10, a student can guess the answer of 4 questions correctly with probability $${3 \over 4}$$ and the remaining 6 questions correctly with probability $${1 \over 4}$$. If the probability that the student guesses the answers of exactly 8 questions correctly out of 10 is $${{{{27}k}} \over {{4^{10}}}}$$, then k is equal to ___________.

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2
JEE Main 2021 (Online) 1st September Evening Shift
Numerical
+4
-1
Change Language
Let X be a random variable with distribution.

x $$ - $$2 $$ - $$1 3 4 6
P(X = x) $${1 \over 5}$$ a $${1 \over 3}$$ $${1 \over 5}$$ b


If the mean of X is 2.3 and variance of X is $$\sigma$$2, then 100 $$\sigma$$2 is equal to :
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3
JEE Main 2021 (Online) 31st August Morning Shift
Numerical
+4
-1
Change Language
An electric instrument consists of two units. Each unit must function independently for the instrument to operate. The probability that the first unit functions is 0.9 and that of the second unit is 0.8. The instrument is switched on and it fails to operate. If the probability that only the first unit failed and second unit is functioning is p, then 98 p is equal to _____________.
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4
JEE Main 2021 (Online) 27th August Evening Shift
Numerical
+4
-1
Change Language
The probability distribution of random variable X is given by :

X 1 2 3 4 5
P(X) K 2K 2K 3K K


Let p = P(1 < X < 4 | X < 3). If 5p = $$\lambda$$K, then $$\lambda$$ equal to ___________.
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