Question

A coin is flipped, and a number cube is rolled. What is the probability of getting heads on the coin and a number less than 3 on the number cube?
a.one eighth
b. one sixth
c. one fourth
d. one half

Answer 1

Answer:  one sixth (choice B)

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Explanation:

The probability of getting heads is 1/2 because there's one side we want out of two sides total

The probability of getting less than 3 is 2/6 = 1/3 since we have two sides we want (rolling a "1" or a "2") out of six sides total.

Multiply the two mentioned fractions: 1/2 times 1/3 = 1/6

1/6 can be written as "one sixth", but I prefer the first format better since it's shorter.

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If you are a visual learner, you can make a table with 2 rows and 6 columns, or vice versa (6 rows and 2 columns). The order doesn't matter.

The two rows represent the events Heads or Tails. The 6 columns show the different outcomes on the number cube. We have 6*2 = 12 different outcomes of rolling a die and flipping a coin.

Of those 12 outcomes, shade in 2 boxes to represent getting heads and either a "1" or "2". Refer to the diagram below.

We have 2 shaded rectangles out of 12 total to get 2/12 = 1/6

The visual representation of a table like this may help show why we multiplied the fractions 1/2 and 1/3 to get the answer. Hint: think of area = length*width.