The rates that Zack charges for baby-sitting are as follows:
-- $2.50 per hour for the first child and
-- an extra 75 cents per hour for each additional child.
Choose the expression that represents the number of dollars that Zack will collect per hour
for babysitting n children.
1
You're on the right track, but it's not quite there. You added a flat 75 cents,
but there's a 75 cent charge for each additional child.
The correct expression is 2.50 + .75(n-1)
Student added in the 75 cents only for a second child.
2
Close, but not quite there. You added 75 cents for all the children, but
the charge is just for additional children.
The correct expression is 2.50 + .75(n-1)
Student added in the additional charge for the first child,
but did everything else right.
3
Correct!
Student got it right.
4
You're on the right track, but it's not quite there.
You forgot the base amount (2.50), and the 75 cents won't apply to all n-1
children the way you have it written. Parentheses are important here.
The correct expression is 2.50 + .75(n-1)
Student did not use the base amount and needs parentheses around the n-1.
5
You're on the right track, but it's not quite there.
The 75 cents won't apply to all n-1
children, the way you have it written. Parentheses are important here.
The correct expression is 2.50 + .75(n-1)
Parentheses need to go around the n-1.
ModelArithmetic
ExplicitArithmetic
VerbalRuleArithmetic