Question

Tommy has a piece of toast that has butter on one side, and he dropped it twice. Both times, it landed with the butter side up. If he drops it two more times, what is the probability that it will have landed butter side up a total of three times?
one over two
one over six
one over four
one over three

Answer 1

Answer:  The correct option is (A) one over two.

Step-by-step explanation:  Given that Tommy has a piece of toast that has butter on one side and he dropped it twice. Both times, it landed with the butter side up.

We are to find the probability that it will land butter side up a total of three times if he drops the piece of bread two more times.

Since the piece of bread has already landed two times with butter side up, so to make it three times landed butter side,

it should land one of the two more times land with butter side up.

Let, S be the sample space for the next two drops.

Then, n(S) = 2.

Let, E be the event that the piece of bread land with butter side up in the next two drops.

Then, n(E) = 1.

Therefore, the probability of event E is given by

$P(E)=\dfrac{n(E)}{n(S)}\\\\\\\Rightarrow P(E)=\dfrac{1}{2}.$

Thus, the required probability that the piece of bread landed three times with butter side up is $\dfrac{1}{2}.$

Option (A) is CORRECT.

Answer 2

Its a one over two chance that the piece of toast won't land on the side with butter