Your sequence appears to be geometric with a common ratio of 2. It can be described by
a(n) = (-2 2/3)·2^(n-1)
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This can be written in a number of other forms, including
a(n) = (-8/3)·2^(n-1)
a(n) = (-1/3)·2^(n+2)
a(n) = (-4/3)·2^n
Yes it is 50 miles per hour
Say your test is out of 100 and you 75 correct to calculate your percent you would go
75/100*100
/ = Divide
* = Times
