Question

a birds watcher saw 3 blue jays on the first day of his vacation. Each day after that he saw 2 more blue jays than he did on the previous day. On the last day he saw 27 blue jays. write an equation that could be solved to find the number of days the birdwatcher was on vacation since the 1st day

Answer 1

The number of days is 13.

Explanation:

It is given that a birds watcher saw 3 blue jays on the first day of his vacation. Each day after that he saw 2 more blue jays than he did on the previous day.

`a_1=3`

`a_2=a_1+2=3+2=5`

`a_3=a_2+2=5+2=7`...

It means the series is

3,5,7,..., 27

The first term of series is 3 and the common differences is 2.

The formula of nth term is

`a_n=a+(n-1)d`

Substitute
`a_n=27`, a=3 and d=2.

`27=3+(n-1)2`

`27=3+2n-2`

`27=1+2n`

`26=2n`

`n=13`

Therefore the number of days is 13.