1
GATE ECE 2012
+2
-0.6
A fair coin is tossed till a head appears for the first time. The probability that the number of required tosses is odd, is
A
$$1/3$$
B
$$1/2$$
C
$$2/3$$
D
$$3/4$$
2
GATE ECE 2010
+2
-0.6
A fair coin is tossed independently four times. The probability of the event ''The number of times heads show up is more than the number of times tails show up'' is
A
$$1/16$$
B
$$1/8$$
C
$$1/4$$
D
$$5/16$$
3
GATE ECE 2009
+2
-0.6
A discrete random variable $$X$$ takes value from $$1$$ to $$5$$ with probabilities as shown in the table. A student calculates the mean of $$X$$ as $$3.5$$ and her teacher calculates the variance to $$X$$ as $$1.5.$$ Which of the following statements is true?
A
Both the student and the teacher are right
B
Both the student and the teacher are wrong
C
The student is wrong but the teacher is right
D
The student is right but the teacher is wrong
4
GATE ECE 2009
+2
-0.6
Consider two independent random variables $$X$$ and $$Y$$ with identical distributions. The variables $$X$$ and $$Y$$ take values $$0, 1$$ and $$2$$ with probability $$1/2,$$ $$1/4$$ and $$1/4$$ respectively. What is the conditional probability $$P(X+Y=2/X-Y=0)?$$
A
$$0$$
B
$$1/16$$
C
$$1/6$$
D
$$1$$
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