courtney earned an 86, 92, 95, and 89 on her first four math tests. there is one more test to take what will she need to earn on
the fifth test in order to get at least a 90 in the course?
1 answer:
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Answer:
Step-by-step explanation:
i hope this is good enough
Answer:
see explanation
Step-by-step explanation:
The common difference d of an arithmetic sequence is
d = -
=
-
Substitute in values and solve for k, that is
5k - 1 - 2k = 6k + 2 - (5k - 1)
3k - 1 = 6k + 2 - 5k + 1
3k - 1 = k + 3 ( subtract k from both sides )
2k - 1 = 3 ( add 1 to both sides )
2k = 4 ⇒ k = 2
--------------------------------------------------------
The n th term of an arithmetic sequence is
=
+ (n - 1)d
= 2k = 2 × 2 = 4 and
d = 5k - 1 - 2k = 3k - 1 = (3 × 2) - 1 = 5
Hence
= 4 + (7 × 5) = 4 + 35 = 39