Answer:
<u>The sequence is</u>
- 1, 1 + 2, 1 + 2 + 3, 1 + 2 + 3 + 4, ...
Each term is the sum of the consecutive numbers from 1 to that number.
<u>The nth term is the sum of the first n numbers:</u>
- aₙ = 1 + 2 + 3 + ... + n
- aₙ = 1/2n(1 + n) (formula for sum of the n terms of arithmetic progression with the first term of 1 and common difference of 1)
- aₙ = n(n + 1)/2
1) The number of circles in the nth pile is n(n + 1)/2
2) When n tends to infinity the number of circles tends to infinity
Using the binomial distribution, it is found that the mean and the standard deviation of variable x are given as follows:

<h3>What is the binomial probability distribution?</h3>
It is the probability of exactly <u>x successes on n repeated trials, with p probability</u> of a success on each trial.
The expected value of the binomial distribution is:
E(X) = np
The standard deviation of the binomial distribution is:

In this problem, we have that the parameters are given as follows:
n = 4, p = 0.75.
Hence the mean and the standard deviation are given as follows:
- E(X) = np = 4 x 0.75 = 3.
More can be learned about the binomial distribution at brainly.com/question/24863377
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Answer:
9 years = .000000706$
Step-by-step explanation:
convert 7% to decimal 0 .07
17,500 x .07 = 1,225
1 year 1,225
2 year 85.75
3 year 6.0
4 year .42
5 year .029
6 year .002
7 year .000144
8 year .000010088
9 years = .000000706$