There is a 1 in 15 chance it could occur. The more numbers you add, the rarer the chance. This does not guarantee that it will occur in 15 tests.
Answer:

Step-by-step explanation:
In order to write the series using the summation notation, first we need to find the nth term of the sequence formed. The sequence generated by the series is an arithmetic sequence as shown;
4, 8, 12, 16, 20...80
The nth term of an arithmetic sequence is expressed as Tn = a +(n-1)d
a is the first term = 4
d is the common difference = 21-8 = 8-4 = 4
n is the number of terms
On substituting, Tn = 4+(n-1)4
Tn = 4+4n-4
Tn = 4n
The nth term of the series is 4n.
Since the last term is 80, L = 4n
80 = 4n
n = 80/4
n = 20
This shows that the total number of terms in the sequence is 20
According to the series given 4 + 8 + 12 + 16 + 20+ . . . + 80
, we are to take the sum of the first 20terms of the sequence. Using summation notation;
4 + 8 + 12 + 16 + 20+ . . . + 80 = 
(-y + 5a - 4) + (3y - a - 5) is simplified to 2y + 4a - 11
Answer:1920
Step-by-step explanation:
Sorry if this is not accurate but here is how your gonna do it
Find the constant speed per hour (The quotient is 80) then multiply that by 24 which you will get 1920 Hopefull this helps and its correct :D