Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:
Re: CR necessary and sufficient [#permalink]
25 Nov 2004, 12:32
X is necessary for Y to happen
Z is sufficient for Y to happen
Can we conclude 1-- If Y happens X happened 2-- IF Y did not happen X did not happen 3-- If Y happened Z happened 4-- If Y did not happen, Z did not happen
Could someone explain ?
I will pick 1 too. But I have a problem with the question stem... If Z is sufficient for Y to happen it implies that just Z is enough for Y to happen then how can X be necessary for Y to happen?
Well Z maybe enough, but X is NECESSARY. Suppose, I can leave my home when my mom returns, but i need to tell her something very imp. before leaving. So it is NECESSARY that she come \s back before I leave. My dad might come back in the middle (which is sufficient for me to leave), but it is not NECESSARY. So I cant leave even when he comes back.. am I making my point clear?