3. Let X ~ B(n, p), 1.e., P(X = k) = (:)»*'(1 – py-* for k e {0, 1, ...,n}. Assume that 0 < p < 1 (note the strict inequali- ties). In this problem, we will show that the peak of B(n, p) (i.e., the largest probability mass) occurs at k z np. In part (c), [·) denotes the floor function, where [a] is defined to be the largest integer less than or equal to a real number r. Denote P(X = k) by Pg. Show that for k € {0,1, -. · , (a) n– 1}, i. P < Pr+1 if k < np – (1 – p) ii. P = Pk+1 if k = np – (1 – p) iii. P > Pk+1 if k > np – (1 – p).

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3. Let X ~ B(n, р), i..,
P(X = k) = (")»*(1 – p)*-*
for k € {0, 1, ...,n}. Assume that 0 <p<1 (note the strict inequali-
ties). In this problem, we will show that the peak of B(n, p) (i.e., the
largest probability mass) occurs at k z np.
In part (c), [·] denotes the floor function, where [r] is defined to be
the largest integer less than or equal to a real number r.
Denote P(X = k) by Pg. Show that for k e {0,1, .,
п - 1},
i. P < Pr+1 if k < np – (1 – p)
ii. Р. — Р+i if k%3D пр- (1 — р)
ii. Р.> P+i if k> пр— (1 — р).
(a)
You only have to give the details of the first case and note that
the other two cases are similar.
(b)
Let t = np – (1 – p). If np is an integer, show that t
satisfies
пр — 1 <t< пр.
Further show that the peak of B(n, p) occurs at exactly k = np.
Transcribed Image Text:3. Let X ~ B(n, р), i.., P(X = k) = (")»*(1 – p)*-* for k € {0, 1, ...,n}. Assume that 0 <p<1 (note the strict inequali- ties). In this problem, we will show that the peak of B(n, p) (i.e., the largest probability mass) occurs at k z np. In part (c), [·] denotes the floor function, where [r] is defined to be the largest integer less than or equal to a real number r. Denote P(X = k) by Pg. Show that for k e {0,1, ., п - 1}, i. P < Pr+1 if k < np – (1 – p) ii. Р. — Р+i if k%3D пр- (1 — р) ii. Р.> P+i if k> пр— (1 — р). (a) You only have to give the details of the first case and note that the other two cases are similar. (b) Let t = np – (1 – p). If np is an integer, show that t satisfies пр — 1 <t< пр. Further show that the peak of B(n, p) occurs at exactly k = np.
(c)
In general, np is not necessarily an integer, and it can be
shown that t satisfies one of the following:
i. [np] –1<t < [np];
ii. t = [np];
iii. [np] <t < [np] + 1.
Show that for the third case, the peak of B(n, p) occurs at k =
[np] + 1.
Transcribed Image Text:(c) In general, np is not necessarily an integer, and it can be shown that t satisfies one of the following: i. [np] –1<t < [np]; ii. t = [np]; iii. [np] <t < [np] + 1. Show that for the third case, the peak of B(n, p) occurs at k = [np] + 1.
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