JEE MATHEMATICS MCQ: COMBINATIONS

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Kunal Gaba has

n

objects, each of weight

w

. He weighs them in pairs and finds the sum of the weights of all possible pairs is

120 \mathrm{~g}

. When his friend Rakshit weighs them in triplets, the sum of all possible weights is

240 \mathrm{~g}

. The value of

n

View answer and explanation

Correct option: B

Option C (4032) is correct because it is calculated by subtracting the number of selections with three consecutive numbers from the total number of selections.

More Questions from COMBINATIONS

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A rectangle of dimension

m \times n

(

m

and

n

being odd) is divided into square of unit length by drawing horizontal and vertical lines. The number of rectangles having side of odd unit length is The number of ways selecting three numbers from 1 to 30, so as to exclude every selection of three consecutive number is: Team A consists of 7 boys and n girls and Team B has 4 boys and 6 girls. If a total of 52 single matches can be arranged between these two teams, when a boy plays against a boy and a girl plays against a girl, then n is equal to The number of ways choosing a committee of 4 woman and 5 men from 10 women and 9 men, if Mr.

A

refuses to serve on the committee when Ms.

B

is a member of the committee, is A man has 7 friends. In how many ways he can invite one or more of them for a tea party? If

{\;^{n + 2}}{C_8}:{\;^{n - 2}}{P_4} = \frac{{57}}{{16}}

, then

n

is equal to