# What is a discrete random variable?  Which of these scenarios could we consider to be a discrete random variable? i) The number of Casio calculators on the floor. ii) The cost of euro to an...

What is a discrete random variable?

Which of these scenarios could we consider to be a discrete random variable?

i) The number of Casio calculators on the floor.

ii) The cost of euro to an american dollar.

iii) The mass of ball taken from a bag.

iv) Length of time needed to release a video game.

embizze | Certified Educator

A discrete random variable is one that can be counted, as opposed to a continuous variable which can only be measured in a range.

(a) the number of calculators is countable, therefore this is discrete. If you say there are 9 Casio calculators on the floor, then there are 9.

(b) The cost of euros to the dollar is continuous -- it takes on fractional (rounded) values. If you say there are 1.03 euros to the dollar, you really are saying that the numbers of euros to a dollar is between 1.025 and 1.035.

(c) The mass of a ball is continuous. A ball that weighs 100g actually weighs somewhere between 99.5g and 100.5g (Depending on the sensitivity of the scale used.)

(d) Length of time is continuous.

-----------------------------------------------------------

(a) is the discrete random variable.

-----------------------------------------------------------