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Maths doubt

CPT 708 views 5 replies

Guest

On the pg 13.38 of our Maths module the 25th and the 26th questions are as follows

25. P(B/A) is only defined when

a. A is a sure event

b.B is a sure event

c. A is not an impossible event

d. B is an impossible event

ans: c

26. P(A/B') is defined only when

a. B is not a sure event

b. B is a sure event

c. B is not an impossible event

d. B is not an impossible event

ans:a

Why can't the answer for the 26th one be c ( since the above answer is given in terms of impossible event ) ??

Replies (5)

intermediate(ipc)course

1460 Points Posted on 29 April 2012

because B is not a sure event,it is a impossible event.

Guest

It isn't mentioned that B is an impossible event. Nothing s mentioned about the

Tejaswi Kasturi

student-cpt

427 Points Posted on 29 April 2012

B' is not an impossible event implies B is not sure because if B is sure the B' will be impossible and P(B') will be zero makimg P(A|B') = P(AnB')/p(B') undefined

Guest

The C option for 26th question is that B is an impossible event.. Thank you for the answer.. But since we need to show that B' is not an impossible event can't we select the C option as it also shows that B' is not an impossible event??

Tejaswi Kasturi

student-cpt

427 Points Posted on 30 April 2012

B is an impossible event is a subset of the events which has b is not a sure event. P(A|B') is defined for all P(B') not equal to zero. so by mentioning answer c you would say that P(A|B') is not defined for anything except when P(B') is 1 which is not true