Answer:
The given sequence 6, 7, 13, 20, ... is a recursive sequence
Step-by-step explanation:
As the given sequence is

- It cannot be an arithmetic sequence as the common difference between two consecutive terms in not constant.
As
, 
As d is not same. Hence, it cannot be an arithmetic sequence.
- It also cannot be a geometrical sequence and exponential sequence.
It cannot be geometric sequence as the common ratio between two consecutive terms in not constant.
As
,
, 
As r is not same, Hence, it cannot be a geometric sequence or exponential sequence. As exponential sequence and geometric sequence are basically the same thing.
So, if we carefully observe, we can determine that:
- The given sequence 6, 7, 13, 20, ... is a recursive sequence.
Please have a close look that each term is being created by adding the preceding two terms.
For example, the sequence is generated by starting from 1.

and

for n > 1.
<em>Keywords: sequence, arithmetic sequence, geometric sequence, exponential sequence</em>
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Answer:
By the Empirical Rule, 
Step-by-step explanation:
The Empirical Rule states that, for a normally distributed random variable:
68% of the measures are within 1 standard deviation of the mean.
95% of the measures are within 2 standard deviation of the mean.
99.7% of the measures are within 3 standard deviations of the mean.
The symbol of a standard deviation is
. So
When plotting sample statistics on a control chart, 99.7% of the sample statistic values are expected to fall within plus/minus how many sigma?
By the Empirical Rule, 
I think its true but i may be wrong
The answer will be 35.8 , i calculated it