# UGC NET Computer Science Previous Paper II June 2009 - Part 1

1.       If x and y are independent Gaussian random variables with average value 0 and with same variance, their joint probability density function is given by:
(A) p(x,y)=p(x).p(y)
(B) p(x,y)=p(x)+p(y)
(C) p(x,y)=p(x+y)
(D) p(x,y)=p(x).p(y)+p(x)
2.       In order that a code is ‘t’ error correcting, the minimum Hamming distance should be:
(A) t
(B) 2t-1
(C) 2t
(D) 2t+1
3.       The Boolean expression x’y’z+yz+xz is equivalent to:
(A) x
(B) y
(C) z
(D) x+y+z
4.       The characteristic equation of a JK flip flop is:
(A) Qn+1=J.Qn+K.Qn
(B) Qn+1=J.Q’n+K’.Qn
(C) Qn+1=QnJ.K
(D) Qn+1=(J+K)Qn
5.       In order to implement a n variable switching function, a MUX must have:
(A) 2n inputs
(B) 2n+1 inputs
(C) 2n-1 inputs
(D) 2n-1 inputs

6.       The throughput of pure ALOHA is given by:
(A) S=G
(B) S=e2G
(C) S=Ge2G
(D) Ge-2G
7.       The Fiber Distributed Data Interface uses:
(A) single mode fibers and LEDs
(B) multimode fibers and LEDs
(C) single mode fibers and ILDs
(D) multimode fibers and ILDs
8.       To employ multi-access in GSM, users are given different:
(A) time slots
(B) bandpass filters
(C) handsets
(D) frequency bands
9.       With a four programs in memory and with 80% average I/O wait, the CPU utilization is?
(A) 60%
(B) 70%
(C) 90%
(D) 100%