What is it?
Eighteen days before Sofia Amandas debut, her parents planned to give her gifts. On the first day,
they gave one gift, on the 2nd day, three. On the 3rd day, five and on the 4 day, seven gifts. How many
gifts did her parents give on the 18 day?
See the table below:
1 3 5 7
? ? ? ? ? ?
Observing the number of gifts she received:
As the sequence continues:
1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35,
Looks like you have the answer in your questions but ok.
We have to find the pattern. For patterns that start on a number and add or subtract the same each time, we have a strategy
a1 + (n – 1) * d
This equation has a1 meaning the first number, n being the term you are looking for and d as the difference between each term.
Lets have a look in your case.
We see that the first day, or term, is 1. We already have that done!
1 + (n – 1) * d.
We then look for “n”, which is what spot, or term we are looking for. We see that the question wants how many gifts she will get on the 18th, so we know that “n” is equal to 18.
1 + (18 – 1) * d
Our final missing variable is the difference. We are looking for how far apart each number is from the next. We can find that here, the difference is 2 as we take any term and subtract it from the next term.
Example: Lets take the second and then subtract it from the 3rd. 5 – 3 = 2 which is the difference
Solve the problem and you get your answer:
1 + (18 – 1) * 2
1 + 17 * 2
1 + 34 = 35 total gifts she will get on the 18th day.
Also some patterns are simple, like instead you could also do 2n – 1 where n is the term you want to get (18 in your case)
Sorry if it didnt help, I just try to help people although im not the best