1)
3)
let's recall that the conjugate of any pair a + b is simply the same pair with a different sign, namely a - b and the reverse is also true, let's also recall that i² = -1.
let n be the number of times letter be found (1800), p be the success rate (0.068), and q be the failure rate (1 - 0.068 = 0.932)
mean = np = 1800 x 0.068 = 122.4
standard deviation = √(npq) = √(1800 x 0.068 x 0.932) = 10.6807414
Make a change of coordinates:
The Jacobian for this transformation is
and has a determinant of
Note that we need to use the Jacobian in the other direction; that is, we've computed
but we need the Jacobian determinant for the reverse transformation (from
to
. To do this, notice that
we need to take the reciprocal of the Jacobian above.
The integral then changes to
1: 5 2: 9 or 10
For question 1 we can round 115 to 100, 5x100 is 500 which is closer to 545 than 7x100 = 700.