Question

The deposits Ginny makes at her bank each month form an arithmetic sequence. The deposit for month 3 is $150, and the deposit for month 5 is $180.
Answer these questions
1.what is common differences for each month? $15
2.write explicit formula for arithmetic sequence
3.amount in 12th month?
4.what month will deposit at least $500?

Answer 1

105+15n
285
month 27
these are my other answers

Answer 2

3 150
4 150 + d
5 150 + 2 d = 180

so d = 30/2 = 15

month 1 = 150-30 = 120

An = 120 + (n-1)15

A12 = 120 + 11(15) = 285 yes correct

500 = 120 + (n-1)15

n - 1 = 25.33
n = 26.33
yes, 27