The problem asks us to estimate how many students are expected to take the bus in a group of 400 students based on a survey of 40 students.

Steps:

1. From the survey, 12 out of 40 students take the bus.
2. We need to scale this proportion to a group of 400 students.

Calculation:

$\text{Proportion of bus riders} = \frac{12}{40} = 0.3$ Now, apply this proportion to the larger group: $\text{Expected number of bus riders in 400 students} = 0.3 \times 400 = 120$

Answer:

In a group of 400 students, 120 students are expected to have taken the bus.

Do you want further details on this?

Here are some related questions:

1. What if the survey included 100 students instead of 40?
2. How can we calculate the number of students expected to walk to school?
3. What if the number of students who took the bus was not a whole number?
4. How would the number of car riders change in a group of 400 students?
5. Can we apply the same method to predict how many students use a bicycle?

Tip: Always verify proportions by comparing smaller group data before extrapolating to a larger one.