Question

Yohanna is conditioning all summer to be fit for the next soccer season at his high school. He incorporated walking planks into his daily workout regime. Each day, he will complete 4 more walking planks than the day before. If he starts with 5 walking planks on the first day, how many walking planks will he do on the twelfth day?

Answer 1

the answer is 49!!

Explanation:

Answer 2

The correct answer is 49.

Explanation:
This can be represented as an arithmetic sequence, since we are adding the same number each time to find the next number. The general rule for an arithmetic sequence is

`a_n=a_1+d(n-1)`,
where a₁ is the first term and d is the common difference.

In this problem, a₁=5, since he starts at 5, and d=4, since he is adding 4 planks per day; this gives us

`a_n=5+4(n-1)`

Letting 12 be n for the 12th day, we have
5+4(12-1)=5+4(11)=5+44=49.