Answer:
<h2>17/35</h2>
Step-by-step explanation:
We need to get all the fractions with a common denominator before we can solve the problem.
The only fractions that have a common multiple are 1/7 and 3/21, so we'll add these first and then add 1/5.
1/7 = 3/21
Add

6/21 = 30/105
1/5 = 21/105

Simplify

<h3>
ANSWER: 17/35</h3>
I'm always happy to help :)
This looks like scalar matrix multiplication. The idea here is to multiply the scalar 3 by each item inside the matrix.
Doing so leads to the answer [3 -12 15 -21]
Side note: I'm assuming the matrix given to you has 1 row and 4 columns.
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, 
The median is 79. Hope this helps!