Answer: common difference is 14
Step-by-step explanation:
a,a+d,a+4d
7,7+d,7+4d
(7+d)/7=(7+4d)/(7+d)
(7+d)(7+d)=7(7+4d)
49+14d+d^2=49+28d
d^2-14d=0
d(d-14)=0
d=0 or d-14=0
d=14
The answer to this question would be the last choice (this data has no outliers)
Explanation: The reason for this is that an outlier is basically any number or value that kind of stands off or is very separated from a set of data.
For example, if I had the numbers 1,2,3,2,9,5,7,5,8,4 and 47, 47 would definitely be an outlier as it's significantly greater than the rest of the data.
The data shown in your question doesn't vary a lot though, (it's contained within a range of 65 and 80- no number seems to be radically different).
15 because simple division 30 divided by 2 is 15 only 15 can happen