Question

Consider the groups: N (natural numbers), Q (rational numbers), Q+ (rational numbers not negatives) and R (real numbers). The number that expresses:

a) the height of someone is an element from N
b) the average speed of a vehicle is a number from Q, but not from Q+
c) the quantity of people from a town is an element from Q+, but not N
d) the value of an ice cream (in dollars) is an element of Q+

I guess it's d, I'm confused now.

Answer 1

Yeah it's d

Answer 2

Natural numbers are whole numbers..
Rational number can be expressed as a fraction..
Real numbers are all numbers..(non imaginary ones)

Answer 3

height can be in fraction, speed has to be positive, quantity of people is always a natural number.
Value of ice cream can be a rational $2/3 or $5

Answer 4

my friend kept telling me that velocity could be negative because of physics stuff D:

Answer 5

a) False, because height doesn't have to be a whole number
b) False, average speed is always positive (velocity could be negative, not speed)
c) Quantity of people is a natural number, you don't express the number of people in fractions - like I have 5 and a half people in my family
d) True, the value of ice cream always has to be positive (assuming that it's not so bad that people want to pay you to take it), and it can be a fraction, such as $2.75

Answer 6

omg sorry guys, I meant velocity, not speed.

Answer 7

So, b or d?

Answer 8

i said b - false. so d

Answer 9

speed cannot be negative

Answer 10

But you said that velocity can be negative

Answer 11

speed != velocity
speed = |velocity|

Answer 12

that's confusing lol are you sure that b is false?