a2zinterviews

11.	In a simultaneous of two dice, what is the probability of getting a toatl of 10 or 11?
	A.  1/4
	B.  1/6
	C.  7/12
	D.  5/36

Solution

In a simultaneous throw of two dice,we have n(S)= (6×6) = 36. Let E = event of getting a total of 10 or 11 = {(4,6),(5,5),(6,4),(5,6),(6,5)}. P(E) = n(E) / n(S) = 5/36.

12.	One card is drawn at random from a pack of 52 cards. What is the probability that the card drawn is a face card?
	A.  1/13
	B.  4/13
	C.  1/4
	D.  9/52

Solution

Clearly, there are 52 cards, out of which there are 16 faces cards. Therefore, P(getting a face card) = 16/52 ‹=›4/13.

13.	Three unbiased coins are tossed.What is the probability of getting at least 2 heads?
	A.  1/2
	B.  1/4
	C.  1/3
	D.  1/8

Solution

Here S= {TTT, TTH, THT, HTT, THH, HTH, HHt, HHH}. Let E = event of getting at least two heads = {THH, HTH, HHT, HHH}. P(E) = n(E) / n(S) = 4/8. ‹=›1/2.

14.	Two dice are thrown together. What is the probability that the sum of the numbers on the two faces is divisible by 4 or 6?
	A.  5/18
	B.  7/18
	C.  9/18
	D.  12/18

Solution

Here, n(S) =(6×6)= 36. Let E be the event that the sum of the numbers on the two faces is divisible by 4 or 6.Then E= {(1,3),(1,5),(2,2),(2,4),(2,6),(3,1),(3,3),(3,5),(4,2),(4,4),(5,1),((5,3),(6,2),(6,6)} Then, n(E) = 14. = 16. Therefore, P(E) = n(E)/n(S) = 14 / 36 = 7 / 18.

15.	An unbiased die is tossed. Find the probability of getting a multiple of 3.
	A.  1/2
	B.  1/4
	C.  1/3
	D.  2/4

Solution

Here S= {1,2,3,4,5,6}. Let E be the event of getting a multiple of 3. Then, E = {3,6}. P(E) = n(E) / n(S) = 2/6 = 1/ 3.