1
WB JEE 2018
MCQ (Single Correct Answer)
+1
-0.25
Change Language
The number of selection of n objects from 2n objects of which n are identical and the rest are different, is
A
2n
B
2n $$-$$ 1
C
2n $$-$$ 1
D
2n $$-$$ 1 + 1
2
WB JEE 2018
MCQ (Single Correct Answer)
+1
-0.25
Change Language
If (2 $$ \le $$ r $$ \le $$ n), then $${}^n{C_r}$$ + 2 . $${}^n{C_{r + 1}}$$ + $${}^n{C_{r + 2}}$$ is equal to
A
2 . $${}^n{C_{r + 2}}$$
B
$${}^{n + 1}{C_{r + 1}}$$
C
$${}^{n + 2}{C_{r + 2}}$$
D
$${}^{n + 1}{C_r}$$
3
WB JEE 2018
MCQ (Single Correct Answer)
+2
-0.5
Change Language
From a collection of 20 consecutive natural numbers, four are selected such that they are not consecutive. The number of such selections is
A
284 $$ \times $$ 17
B
285 $$ \times $$ 17
C
284 $$ \times $$ 16
D
285 $$ \times $$ 16
4
WB JEE 2017
MCQ (Single Correct Answer)
+1
-0.25
Change Language
The number of all numbers having 5 digits, with distinct digits is
A
99999
B
$$9 \times {}^9{P_4}$$
C
$${}^{10}{P_5}$$
D
$${}^9{P_4}$$
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