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Match List-I with List-II

List-IList-II
(A) The number of different words that can be formed with CUSTOM with the condition that the word should begin with M is ______.(I) 70
(B) The number of different ways in which the letters of the word EXTRA can be arranged so that the vowels are never together is ______.(II) 45
(C) There are 10 points in a plane. No three of these points are in a straight line. The total number of straight line that can be formed by joining the two points is _______.(III) 72
(D) The number of ways a committee of 4 people be chosen out of 8 people is _______.(IV) 120

Choose the correct answer from the options given below:

Solution

✅ Correct Option: 4

(A) Words starting with M from CUSTOM

Word CUSTOM has 6 letters: C, U, S, T, O, M

M is fixed at the first position. The remaining 5 letters need to be arranged.

Remaining letters: C, U, S, T, O

Number of ways =5!= 5!

=5×4×3×2×1= 5 \times 4 \times 3 \times 2 \times 1

=120= 120

(A) matches with (IV) 120


(B) Arranging EXTRA so vowels are never together

Word EXTRA has 5 letters

Vowels: E, A (2 vowels)

Consonants: X, T, R (3 consonants)

Total arrangements =5!=120= 5! = 120

For arrangements where vowels ARE together, treat (EA) as one unit.

Units to arrange: (EA), X, T, R (4 units)

Arrangements of 4 units =4!=24= 4! = 24

E and A can swap within the unit =2!=2= 2! = 2

Arrangements with vowels together =24×2=48= 24 \times 2 = 48

Arrangements with vowels never together =120−48= 120 - 48

=72= 72

(B) matches with (III) 72


(C) Straight lines from 10 points (no 3 collinear)

10 points are available with no 3 points in a straight line.

A line requires 2 points. Order doesn't matter.

Number of lines =C(10,2)= C(10,2)

=10!2!×8!= \dfrac{10!}{2! \times 8!}

=10×92= \dfrac{10 \times 9}{2}

=45= 45

(C) matches with (II) 45


(D) Committee of 4 people from 8 people

Total people: 8

Need to choose: 4

Order doesn't matter for a committee.

Number of ways =C(8,4)= C(8,4)

=8!4!×4!= \dfrac{8!}{4! \times 4!}

=8×7×6×54×3×2×1= \dfrac{8 \times 7 \times 6 \times 5}{4 \times 3 \times 2 \times 1}

=168024= \dfrac{1680}{24}

=70= 70

(D) matches with (I) 70


Final Matching:

List-IList-II
(A) CUSTOM starting with M(IV) 120
(B) EXTRA vowels never together(III) 72
(C) Lines from 10 points(II) 45
(D) Committee of 4 from 8(I) 70

Correct Answer: (A) - (IV), (B) - (III), (C) - (II), (D) - (I)

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