1
JEE Advanced 2021 Paper 2 Online
MCQ (More than One Correct Answer)
+4
-2 Let

$${S_1} = \left\{ {(i,j,k):i,j,k \in \{ 1,2,....,10\} } \right\}$$,

$${S_2} = \left\{ {(i,j):1 \le i < j + 2 \le 10,i,j \in \{ 1,2,...,10\} } \right\}$$,

$${S_3} = \left\{ {(i,j,k,l):1 \le i < j < k < l,i,j,k,l \in \{ 1,2,...,10\} } \right\}$$ and

$${S_4} = \{ (i,j,k,l):i,j,k$$ and $$l$$ are distinct elements in {1, 2, ...., 10}.

If the total number of elements in the set Sr is nr, r = 1, 2, 3, 4, then which of the following statements is(are) TRUE?
A
n1 = 1000
B
n2 = 44
C
n3 = 220
D
$${{{n_4}} \over {12}} = 420$$
2
IIT-JEE 1998
MCQ (More than One Correct Answer)
+2
-0.5
An n-digit number is a positive number with exactly digits. Nine hundred distinct n-digit numbers are to be formed using only the three digits 2, 5 and 7. The smallest value of n for which this is possible is
A
6
B
7
C
8
D
9
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