Question

Jakob rolls an 8-sided die that is numbered from 1 through 8 a total of 400 times. About how many times should Jakob expect to roll a 5?
50
80
250
350

Answer 1

To find the expected number of times Jakob rolls a 5 when rolling an 8-sided die 400 times, we can use the concept of probability.

The probability of rolling a 5 on a single roll of the die is:

\[
P(rolling \, a \, 5) = \frac{1}{8}
\]

Now, to find the expected number of times Jakob rolls a 5 in 400 rolls, we multiply the total number of rolls by the probability of rolling a 5:

\[
\text{Expected number of 5s} = P(rolling \, a \, 5) \times \text{Total rolls}
\]
\[
\text{Expected number of 5s} = \frac{1}{8} \times 400 = 50
\]

Thus, Jakob should expect to roll a 5 about **50 times**. The answer is:

**50**