1
WB JEE 2022
+1
-0.25

A determinant is chosen at random from the set of all determinants of order 2 with elements 0 or 1 only. The probability that the determinant chosen is non-zero is

A
$${3 \over {16}}$$
B
$${3 \over 8}$$
C
$${1 \over 4}$$
D
$${5 \over 8}$$
2
WB JEE 2021
+1
-0.25
Four persons A, B, C and D throw and unbiased die, turn by turn, in succession till one gets an even number and win the game. What is the probability that A wins the game if A begins?
A
$${1 \over 4}$$
B
$${1 \over 2}$$
C
$${7 \over 15}$$
D
$${8 \over 15}$$
3
WB JEE 2020
+1
-0.25
Four persons A, B, C and D throw an unbiased die, turn by turn, in succession till one gets an even number and win the game. What is the probability that A wins if A begins?
A
$${1 \over 4}$$
B
$${1 \over 2}$$
C
$${7 \over 12}$$
D
$${8 \over 15}$$
4
WB JEE 2020
+1
-0.25
A rifleman is firing at a distant target and has only 10% chance of hitting it. The least number of rounds he must fire to have more than 50% chance of hitting it at least once, is
A
5
B
7
C
9
D
11
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