MEDIUM
Earn 100

Consider a cube of side length 9 units. Let x,y,z be coordinates of points on or inside the cube such that x,y,zI and 0x,y,z9. If total number of ways of selecting two distinct points among these such that their mid-point is also having integral coordinates is N, then which of the following is/are TRUE?

50% studentsanswered this correctly

Important Questions on Permutation and Combination

MEDIUM
Number of divisors of the form 4n+2,n0 of the integer 240 is
MEDIUM
Let n be a non-negative integer. Then the number of divisors of the form 4n+1 of the number 1010·1111·1313 is equal to _____.
HARD
A positive integer k, is perfect if the sum of its positive divisors equals 2k. If n, is a perfect number, then the sum of the reciprocal of its positive divisors
MEDIUM
The total number of 3-digit numbers whose sum of digits is 10, is ..........
MEDIUM

If α and β are the greatest divisors of nn2-1 and 2nn2+2 respectively for all nN, then αβ=

HARD
Let X be a set with exactly 5 elements and Y be a set with exactly 7 elements. If α is the number of one-one functions from XY and β is the number of onto functions from YX, then the value of 15!β-α is _____-.
EASY
The sum of factors of 8! which are odd and are of the form 3m+2, where m is a natural number, is
EASY
The number of ways in which 9 persons can be divided into three equal groups is
HARD
Let N be the least positive integer such that whenever a non-zero digit C is written after the last digit of N, the resulting number is divisible by C. The sum of the digits of N is
HARD
If the integers from 1 to 2021 are written as a single integer like 1239101120202021, then the 2021st digit (counted from the left) in the resulting number is
MEDIUM
An engineer is required to visit a factory for exactly four days during the first 15 days of every month and it is mandatory that no two visits take place on consecutive days. Then the number of all possible ways in which such visits to the factory can be made by the engineer during 1-15 June 2021 is_____
MEDIUM
Let m=9n2+54n+809n2+45n+549n2+36n+35. The greatest positive integer which divides m, for all positive integers n is
MEDIUM
In a hotel, four rooms are available. Six persons are to be accommodated in these four rooms in such a way that each of these rooms contains at least one person and at most two persons. Then the number of all possible ways in which this can be done is_____
HARD
The number of points, having both co-ordinates as integers, that lie in the interior of the triangle with vertices 0, 0, 0, 41 and 41, 0 is
MEDIUM

Consider the following statements
i. Number of ways of placing 'n' objects in k bins kn ) such that no bin is empty is Ck-1(n-1)

ii. Number of ways of writing a positive integer " n ' into a sum of k positive integers is Ck-1(n-1)

iii. Number of ways of placing ' n ' objects in k bins such that at least one bin is non-empty is Ck-1(n-1)

iv. Ckn-Ckn-1=Ck-1(n-1)

HARD
The total number of positive integral solutions x, y, z such that xyz=24 is :
MEDIUM
A natural number has prime factorization given by n=2x3y5z, where y and z are such that y+z=5 and y-1+z-1=56,y>z. Then the number of odd divisors of n, including 1, is:
MEDIUM

If a is the number of all even divisors and b is the number of all odd divisors of the number 10800, then 2a+3b=

MEDIUM
Let S be the set of all ordered pairs x,y of positive integers, with HCFx,y=16 and LCMx,y=48000. The number of elements in S is