Question

At a stop sign, some drivers come to a full stop, some come to a rolling stop' (not a full stop, but slow down), and some do not stop at all. We would like to test if there is an association between gender and type of stop (full, rolling, or no stop). We collect data by standing a few feet from a stop sign and taking note of type of stop and the gender of the driver. Below is a contingency table summarizing the data we collected.
Male Female

Full stop 6 6
Rolling stop 16 15
No stop 4 3
If gender is not associated with type of stop, how many males would we expect to not stop at all?

A. 6.24
B. 5.76
C. 3.64
D. 3.36

Answer 1

Answer:

Option C.

Step-by-step explanation:

Given information:

Male-Full stop = 6, Male-Rolling stop = 16, Male-No stop = 4

Female-Full stop = 6, Female-Rolling stop = 15, Female-No stop = 3

Using the given information we get

Total number of males = 6 + 16 + 4 = 26

Total number of males = 6 + 15 + 3 = 24

Probability of No stop is

$p=\dfrac{\text{No-stop}}{Total}$

$p=\dfrac{4+3}{50}$

$p=\dfrac{7}{50}$

We need to find the number of males that would we expect to not stop at all.

Expected number of males = Number of males × Probability

Expected number of males = $26\times \dfrac{7}{50}$

Expected number of males = $3.64$

Therefore, the correct option is C.