Probability - Heads

Question

Two coins are tossed with probability landing at Head not equal to 0.5. What is the probability of getting two Heads out of two tosses? 

(1) The probability of getting head is 3 times that of getting tails. 
(2) The probability of getting one Head and one Tail is 2/9

ssumitsh · Answer

A.

P(head) = 3 P(tail)
Also P(head) + P(tail) = 1

So P(head) and P(tail) and therefore P(both heads) can be calculated.

B is insufficient. All it tells is P(A)*P(B)

rxs0005 · Answer

I would have to go with C as the Q is asking for the exact value 

so we can get it from 

a*b = 2/9 

and a = 3b

cloaked_vessel · Answer

Is this analysis correct?

We know that p(h)+p(t)=1
From condition 1: p(h)=3p(t)

Let x = p(t) where 0<x<1:

Then we have: 3x+x=1; Thus x=.25, and p(h)=3x=.75

Thus 1 is sufficient:

From 2, we can't get anything, so final answer is A

vprabhala · Answer

i would go with A. explanation as above.

rxs0005 · Answer

guys the above calculation will work for 1 coin but 2 coins are tossed

What is the OA ?

mallelac · Answer

I would go with B.

P(Two coins with no heads) = 0.5

P(one head and one tail + all heads) = 1-0.5 = 0.5

(1)Insufficient for the above equation
(2)Sufficient because P(one head and one tail ) = 2/9
 P(all heads) = P(one head and one tail + all heads) - P(one head and one tail ) = 1/2 - 2/9 = 5/18

Thus, it is B.

mallelac · Answer

Could you justify the OA? Somehow, I could not!!

I appreciate if you let me know why I am wrong in choosing B. That helps me a lot.

Probability - Heads

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