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If for some m, n; 6Cm+2 (6Cm+1 )+6Cm+2>8C3 and n-1P3:nP4=1:8, then nPm+1+n+1Cm is equal to
(3) 372
6Cm+2 6Cm+1+6Cm+2= (6Cm+6Cm+1 )+ (6Cm+1+6Cm+2 )=7Cm+1+7Cm+2=8Cm+2
∵ nCr+nCr+1=n+1Cr+1
8Cm+2>8C3=56 and 8Cr exceeds 56 only for r=4 (8C4=70) m+2=4 m=2
n-1P3nP4= (n-1)(n-2)(n-3)n(n-1)(n-2)(n-3)= 1n= 18 n=8
8P3+9C2=336+36=372
Answer: (3)
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