Answer:
an = 115 + (n - 1) (-6)
a25 = - 29
Step-by-step explanation:
We use the definition for the nth term of an arithmetic sequence:
an = a1 + (n - 1) d
a5 = 91 = a1 + (5 - 1) d
91 = a1 + 4 d
a20 = 1 = a1 + (20 - 1) d = a1 + 19 d
1 = a1 + 19 d
now we subtract term by term one expression from the other
90 = 4 d - 19 d
90 = - 15 d
divide both sides by -15 to isolate d
d = 90 / (-15) = -6
Now we can calculate what a1 is using for example:
1 = a1 + 19 d
1 = a1 - 114
add 114 to both sides:
115 = a1
Then our general expression for the sequence is:
an = 115 + (n - 1) (-6)
We can now use it to calculate the value of a25:
a25 = 115 + (24) * (-6) = -29
Answer:
The z- score for a value of 3.99 will be 3.38.
Step-by-step explanation:
It is given that the mean of a set of data is -3.82 and its standard deviation is 2.31.
Thus, the value of the z-score=
=
=
=
=
Thus, the z- score for a value of 3.99 will be 3.38.
ANSWER
The 4th term is -27
EXPLANATION
The sum of the first n-terms of an arithmetic sequence is
It was given that,
The n-term is given by:
We substitute n=4 to get,
The correct answer is sss
Answer:
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Step-by-step explanation:
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