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Match List-I with List-II

List-IList-II
(A) 8P3−10C3^8P_3 - ^{10}C_3(I) 6
(B) 8P5^8P_5(II) 21
(C) nP4=360^nP_4 = 360, then find n.(III) 216
(D) nC2=210^nC_2 = 210, find n.(IV) 6720

Choose the correct answer from the options given below:

Solution

✅ Correct Option: 3

The formula for permutation is nPr=n!(n−r)!^nP_r = \frac{n!}{(n-r)!}

8P3=8!(8−3)!^8P_3 = \frac{8!}{(8-3)!}

=8!5!= \frac{8!}{5!}

=8×7×6= 8 \times 7 \times 6

=336= 336

The formula for combination is nCr=n!r!(n−r)!^nC_r = \frac{n!}{r!(n-r)!}

10C3=10!3!×7!^{10}C_3 = \frac{10!}{3! \times 7!}

=10×9×83×2×1= \frac{10 \times 9 \times 8}{3 \times 2 \times 1}

=7206= \frac{720}{6}

=120= 120

Therefore:

8P3−10C3=336−120^8P_3 - ^{10}C_3 = 336 - 120

=216= 216

(A) matches with (III) 216


8P5=8!(8−5)!^8P_5 = \frac{8!}{(8-5)!}

=8!3!= \frac{8!}{3!}

=8×7×6×5×4= 8 \times 7 \times 6 \times 5 \times 4

=6720= 6720

(B) matches with (IV) 6720


nP4=n(n−1)(n−2)(n−3)=360^nP_4 = n(n-1)(n-2)(n-3) = 360

For n=6n = 6:

6×5×4×3=3606 \times 5 \times 4 \times 3 = 360

(C) matches with (I) 6


nC2=n(n−1)2=210^nC_2 = \frac{n(n-1)}{2} = 210

n(n−1)=420n(n-1) = 420

For n=21n = 21:

21×20=42021 \times 20 = 420

4202=210\frac{420}{2} = 210

(D) matches with (II) 21


Final Matching:

(A) → (III) 216

(B) → (IV) 6720

(C) → (I) 6

(D) → (II) 21

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