The expected length of code for one encoded symbol is

where
is the probability of picking the letter
, and
is the length of code needed to encode
.
is given to us, and we have

so that we expect a contribution of

bits to the code per encoded letter. For a string of length
, we would then expect
.
By definition of variance, we have
![\mathrm{Var}[L]=E\left[(L-E[L])^2\right]=E[L^2]-E[L]^2](https://tex.z-dn.net/?f=%5Cmathrm%7BVar%7D%5BL%5D%3DE%5Cleft%5B%28L-E%5BL%5D%29%5E2%5Cright%5D%3DE%5BL%5E2%5D-E%5BL%5D%5E2)
For a string consisting of one letter, we have

so that the variance for the length such a string is

"squared" bits per encoded letter. For a string of length
, we would get
.
In a triangle, the midsegment is parallel to and half of non-intersecting side.
I think the answer is par
Answer:
Step-by-step explanation:
<u>Total number of outcomes:</u>
<u>Number of combinations of getting 6 heads:</u>
- 15C6 = 15!/6!(15-6)! = 5005
<u>Required probability is:</u>
- P(6 heads out of 15 flips) = 5005/32768 = 0.1527... ≈ 15.3%
Correct choice is D
The answer to this problem is 2/5