Question

Please help and thank you

Answer 1

The answer is B...

On the first day he spends 30 minutes training.. after that he is spending 10 minutes extra.. so on day two he would spend 40 minutes.. then day three.. 50 minutes.. day four.. 60 minutes and so on... The answer would be B though.

Answer 2

Answer: B. 8th day: 100 minutes; 9th day: 110 minutes; 10th day: 120 minutes

Remember:

$a_{n}$ = $n$th term

$n$ = number of terms

$a_{1}$ = first term

$d$ = common difference

Identify the given information.

$a_{1} = 30\\d = 10$

Choose which formula to use. In this case, you should use the explicit formula for arithmetic sequences.

$a_{n} = a_{1} + d(n - 1)$

Substitute in the given values and simplify.

$a_{n} = 30 + 10(n - 1)\\a_{n} = 30 + 10n - 10\\a_{n} = 10n + 20$

Substitute in 8, 9, and 10 for $n$ to find out how many days Rick would train on the 8th, 9th, and 10th day of training.

$a_{8} = 10(8) + 20 = 80 + 20 = 100\\a_{9} = 10(9) + 20 = 90 + 20 = 110\\a_{10} = 10(10) + 20 = 100 + 20 = 120$