Question

20 PTS!! The cost of a hamburger is $2.50. Each additional hamburger costs $1.00. Sully wrote this explicit rule to explain the sequence of costs: f(n) = 1 + 2.5(n − 1). Using this rule, he found the cost of 12 hamburgers to be $28.50. Is this number correct? If not, identify Sully's error.

Answer 1

$13.50

Explanation:

Sully's error is the formula:

f(1)=2.5

f(2)=2.5+1

f(3)=2.5+1+1

f(4)=2.5+1+1+1

and so on...

So the formula should be:

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

f(12)= 2.5+ 11 = 13.5