1
GATE CSE 2008
MCQ (Single Correct Answer)
+2
-0.6
What is the probability that in a randomly choosen group of r people at least three people have the same birthday?
A
$$1 - {{365.364....\,(365\, - \,r\, + \,1)} \over {{{365}^r}}}$$
B

$$ {{365.364....\,(365\, - \,r\, + \,1)} \over {{{365}^r}}}$$
$$ + {\,^r}{C_2}.\,365.{{364.363....\,(364\, - \,(r - 2)\, + \,1)} \over {{{365}^{r - 2}}}}$$
C
$$1 - {{365.364....\,(365\, - \,r\, + \,1)} \over {{{365}^r}}}$$
$$ - {\,^r}{C_2}.\,365.{{364.363....\,(364\, - \,(r - 2)\, + \,1)} \over {{{365}^{r - 2}}}}$$
D
$${{365.364....\,(365\, - \,r\, + \,1)} \over {{{365}^r}}}$$
2
GATE CSE 2008
MCQ (Single Correct Answer)
+2
-0.6
Which of the following is the negation of $$$\left[ {\forall x,\alpha \to \left( {\exists y,\beta \to \left( {\forall u,\exists v,\gamma } \right)} \right)} \right]?$$$
A
$$\left[ {\exists x,\alpha \to \left( {\forall y,\beta \to \left( {\exists u,\forall v,\gamma } \right)} \right)} \right]$$
B
$$\left[ {\exists x,\alpha \to \left( {\forall y,\beta \to \left( {\exists u,\forall v,\neg \gamma } \right)} \right)} \right]$$
C
$$\left[ {\forall x,\neg \alpha \to \left( {\exists y,\neg \beta \to \left( {\forall u,\exists v,\neg \gamma } \right)} \right)} \right]$$
D
$$\left[ {\exists x,\alpha \wedge \left( {\forall y,\beta \wedge \left( {\exists u,\forall v,\neg \gamma } \right)} \right)} \right]$$
3
GATE CSE 2008
MCQ (Single Correct Answer)
+2
-0.6
$$P$$ and $$Q$$ are two propositions. Which of the following logical expressions are equivalent?

$${\rm I}.$$ $${\rm P}\, \vee \sim Q$$
$${\rm I}{\rm I}.$$ $$ \sim \left( { \sim {\rm P} \wedge Q} \right)$$
$${\rm I}{\rm I}{\rm I}.$$ $$\left( {{\rm P} \wedge Q} \right) \vee \left( {{\rm P} \wedge \sim Q} \right) \vee \left( { \sim {\rm P} \wedge \sim Q} \right)$$
$${\rm I}V.$$ $$\left( {{\rm P} \wedge Q} \right) \vee \left( {{\rm P} \wedge \sim Q} \right) \vee \left( { \sim {\rm P} \wedge Q} \right)$$

A
Only $${\rm I}$$ and $${\rm I}$$$${\rm I}$$
B
Only $${\rm I}$$, $${\rm I}$$$${\rm I}$$ and $${\rm I}$$$${\rm I}$$$${\rm I}$$
C
Only $${\rm I}$$, $${\rm I}$$$${\rm I}$$ and $${\rm I}$$$$V$$
D
All of $${\rm I}$$, $${\rm I}$$$${\rm I}$$, $${\rm I}$$$${\rm I}$$$${\rm I}$$ and $${\rm I}$$$$V$$
4
GATE CSE 2008
MCQ (Single Correct Answer)
+2
-0.6
Which of the following first order formulae is logically valid? Here $$\alpha \left( x \right)$$ is a first order formulae with $$x$$ as a free variable, and $$\beta $$ is a first order formula with no free variable.
A
$$\left[ {\beta \to \left( {\exists x,\alpha \left( x \right)} \right)} \right] \to \left[ {\forall x,\beta \to \alpha \left( x \right)} \right]$$
B
$$\left[ {\exists x,\beta \to \alpha \left( x \right)} \right] \to \left[ {\beta \to \left( {\forall x,\alpha \left( x \right)} \right)} \right]$$
C
$$\left[ {\left( {\exists x,\alpha \left( x \right)} \right) \to \beta } \right] \to \left[ {\forall x,\alpha \left( x \right) \to \beta } \right]$$
D
$$\left[ {\left( {\forall x,\alpha \left( x \right)} \right) \to \beta } \right] \to \left[ {\forall x,\alpha \left( x \right) \to \beta } \right]$$
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