whats the answer

Question

The cost of a hamburger is $2.50. Each additional hamburger costs $2.00. Sully wrote this explicit rule to explain the sequence of costs: 

f(n) = 2 + 2.5(n − 1).

 Using this rule, he found the cost of 14 hamburgers to be $34.50. Is this number correct? If not, identify Sully's error.

 

Answer 1

Hi, Vivia.

No, this rule is incorrect.

He should have put:

f(n) = 2.5 + 2(n - 1).

Since the first hamburger is $2.50 and each additional hamburger is $2.00