Question

Whats the difference between the rate and initial amount? Like for the question :
Julio takes his brother to a music store. The music store sells CDs for $15 each. If Julio and his brother have $50, how many CDs can they buy? ////////The answers choices are :

$15 = rate; $50 = initial amount

$15 = initial amount; $50 = rate

$15 = rate; -$50 = initial amount

$15 = initial amount; -$50 = rate

Answer 1

Initial amount is how much you start with, the rate is how much something goes up or down per unit. In this case, each CD they buy, their money goes down by a certain number.

Answer 2

But why are some of the answers negative?

Answer 3

Initial amounts *can* be negative. For example, if the initial temperature is -20 degrees and it goes up 5 degrees per hour, then in 6 hours, it will be 10 degrees. Similarly, rates can be negative...if the amount is going up, it should be a positive rate, and if it's going down, it should be a negative rate.

And honestly, the rate in this problem should be negative, since the amount of money is going down (you're buying CDs), so I'd say NONE of these answers are right.

Answer 4

Thanks!