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seen May 22 at 21:02

Oct
4
revised Least Squares Derivation
Elaborated and gave a proof.
Oct
4
answered Least Squares Derivation
Oct
4
comment Why does negative binomial random variable uses ${n-1 \choose r-1}$ instead of ${n \choose r}$ as coefficient?
No we are not skipping the last trial.However note that last trial is not guaranteed success,it is success with probability $p$.Hence we multiplied by $p$,otherwise we'ld have got ${n-1 \choose r-1} {(1-p)}^{(n-r)}p^{(r-1)}$
Oct
4
awarded  Teacher
Oct
4
comment Why does negative binomial random variable uses ${n-1 \choose r-1}$ instead of ${n \choose r}$ as coefficient?
Consider again,if we use $n \choose r$ then it includes the possibility that first r were successes and remaining were failures,then we don't get nth trial as success.For nth trial to be rth success as we want,we only have freedom in choosing $r-1$ successes from $n-1$ trials as rth success is to occur at nth trial.
Oct
4
answered Why does negative binomial random variable uses ${n-1 \choose r-1}$ instead of ${n \choose r}$ as coefficient?
Oct
4
answered Finding the slope of a function
Oct
4
answered how to find the quartiles
Oct
4
awarded  Editor
Oct
4
revised Power series of a function
answer was null and void.
Oct
4
answered Power series of a function