Given:
The arithmetic sequence is −15, −33, −51, −69.
To find:
The nth term of the arithmetic sequence.
Solution:
We have,
−15, −33, −51, −69
Here,
First term: a = -15
Common difference is
Now, nth term of an arithmetic sequence is
Substitute a=-15 and d=-18.
Therefore, the nth term of the given arithmetic sequence is .
Average reading score is given by the expression,
y = 0.153x + 255.4
Here, x in the number of years past 1970.
To find the year in which the average reading score is 259.378, substitute the value of 'y' in the given expression.
y = 0.153x + 255.4
259.378 = 0.153(x) + 255.4
0.153x = 259.378 - 255.4
0.153x = 3.978
x =
x = 26
That means given average reading score 259.378 will be 26 years after 1970.
Therefore, 1996 is the year in which the average reading score will be 259.378.
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