Question

Lewis rolls a number cube and then chooses a card from a set of cards numbered 1 through 5. What is the probability that he will roll an even number and choose an even numbered card?

Answer 1

Answer:

$\frac{1}{5}=0.2$

Step-by-step explanation:

The general formula for a probability is:

$P=\frac{FavorableEvent}{TotalEvents}$

The favorable events for the cube to fall in a even number are:

2, 4, and 6 ⇒ 3 favorable events

and in the cube the total events are:

1, 2, 3, 4, 5, 6 ⇒ 6 total events

So the probability of rolling an even number in the cube is:

$P=\frac{3}{6}\\\\\\ P=\frac{1}{2}$

Now we do something similar to find the probability to choose a card with an even number.

The favorable events for an even numbered card are:

2, 4 ⇒ 2 favorable events

and the total number of events in the cards is:

1, 2, 3, 4, 5 ⇒ 5 total events

Thus, the probability to choose an even numbered card (according to the probability formula) is:

$P=\frac{2}{5}$

And finally, since we want both things to happen we must multiply both obtained probabilities:

• the probability that he will roll an even number and choose an even numbered card:

$P=\frac{1}{2}*\frac{2}{5} \\ \\P=\frac{2}{10} \\\\P=\frac{1}{5} =0.2$

The probability is 1/5 which is equal to 0.2 or 20%