Answer:
You can prove this statement as follows:
Step-by-step explanation:
An odd integer is a number of the form
where
. Consider the following cases.
Case 1. If
is even we have:
.
If we denote by
we have that
.
Case 2. if
is odd we have:
.
If we denote by
we have that 
This result says that the remainder when we divide the square of any odd integer by 8 is 1.
9 because if you subtract 11 from 19 you het 9
P(at least 5 rolls until 1) = P(4 rolls are not 1) = 5/6 x 5/6 x 5/6 x 5/6 = 0.4823 (4sf)
Fewer than 7 rolls to get second 1 after first takes 3 rolls means second occurs on 4th, 5th or 6th roll
The probability of each of these is 1/6, 5/6 x 1/6 and 5/6 x 5/6 x 1/6 respectively.
P(second 1 on 4th, 5th or 6th roll) = 1/6 + 5/36 + 25/216 = 91/216 = 0.4213 (4sf)
It’s an obtuse triangle, this is because none of the sides/angles are equal to one another. Hope this helped you