1
JEE Main 2021 (Online) 25th February Morning Slot
+4
-1
When a missile is fired from a ship, the probability that it is intercepted is $${1 \over 3}$$ and the probability that the missile hits the target, given that it is not intercepted, is $${3 \over 4}$$. If three missiles are fired independently from the ship, then the probability that all three hit the target, is :
A
$${3 \over 4}$$
B
$${3 \over 8}$$
C
$${1 \over 27}$$
D
$${1 \over 8}$$
2
JEE Main 2021 (Online) 25th February Morning Slot
+4
-1
The coefficients a, b and c of the quadratic equation, ax2 + bx + c = 0 are obtained by throwing a dice three times. The probability that this equation has equal roots is :
A
$${1 \over {72}}$$
B
$${5 \over {216}}$$
C
$${1 \over {36}}$$
D
$${1 \over {54}}$$
3
JEE Main 2021 (Online) 24th February Evening Slot
+4
-1
The probability that two randomly selected subsets of the set {1, 2, 3, 4, 5} have exactly two elements in their intersection, is :
A
$${{135} \over {{2^9}}}$$
B
$${{65} \over {{2^8}}}$$
C
$${{65} \over {{2^7}}}$$
D
$${{35} \over {{2^7}}}$$
4
JEE Main 2021 (Online) 24th February Morning Slot
+4
-1
An ordinary dice is rolled for a certain number of times. If the probability of getting an odd number 2 times is equal to the probability of getting an even number 3 times, then the probability of getting an odd number for odd number of times is :
A
$${5 \over {36}}$$
B
$${3 \over {16}}$$
C
$${1 \over 2}$$
D
$${1 \over {32}}$$
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Modern Physics
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