Please help with this sum

vinitrathi1 wrote:Q.A man can hit a target once in 4 shots. If he fires 4 shots in succession, what is the probability that he will hit his target?

1. 1
2. 1/256
3. 81/256
4. 175/256
5. 144/256

Another way to solve this is to say that P(hit target at least once in 4 tries) = 1 - P(hit target zero times in 4 tries)

P(hit target zero times in 4 tries)=(3/4)(3/4)(3/4)(3/4)=81/256

So, P(hit target at least once in 4 tries) = 1 - 81/256
=175/256

Cheers,
Brent

this is another problem on which the issue is bad wording -- "a man can hit a target once in 4 shots" is ambiguous.
pemdas is interpreting this statement as "out of exactly 4 shots, exactly 1 will hit the target". brent is reading it as "he has a 1/4 chance of hitting the target, regardless of what has already happened."

brent's interpretation is more in line with my own intuition about what the writers *meant* to say, but the question is genuinely ambiguous.

in any case, though --
i can see that some posters (pemdas in particular) don't know the source of the problem.

i'll ask the same question i've asked about a thousand times:
IF YOU DON'T KNOW THE SOURCE, WHY ARE YOU USING THE PROBLEM?

do not use problems from unknown third-party sources -- most of them are TERRIBLE, and many (if not most) of them will basically cause you to un-learn, or get confused about, the things that you're supposed to learn.

pemdas wrote: i doubt any one with much less education/schooling than us at BTG, ever buys beans at the groceries store without the origin, expiry codes

well done.