1. Unit 7. Day 2.

2. We want information on a large population.
We don’t/can’t check everything/everybody
Q: What do we do?
A: We take a
sample of the population
REPRESENTATIVE
Random selection
from the larger population
Using a goldilocks amount
Q: Why is it important that the selection is random?
A: Best way to ensure that the sample represents the population

3. San Bernardino High School
2,000 students
80% Hispanic/Latino
10% Black
10% White/Asian/Other

4. San Bernardino High School
2,000 students
80% Hispanic/Latino
10% Black
10% White/Asian/Other
Is this a good sample?:

5. San Bernardino High School
2,000 students
80% Hispanic/Latino
10% Black
10% White/Asian/Other
Is this a good sample?:

6. Today’s Lesson
Group A: Find the percent of F’s in Period 1
5 Groups
Group B: Find the percent of F’s in Period 2
Group C: Find the percent of F’s in Period 3
Group D: Find the percent of F’s in Period 4
Group E: Find the percent of F’s in Period 5

7. Per 1 F D D F C B C C F C F C % C D C B C D B B A C A C
15 %
Per 2 A B C C B D C A C B B C % B A C D C D D D F C C D
Per 3 C D C B B D B C F C D B % C D C D F A D D B A A C
Per 4 B D D C C F A D F F B C % B A B C A D B D B F F C
Which group has the best (most representative) sample?
How could we get a better sample?
Per 5 A B C D F A B B F A C F
25 % C B C D C F C F D D A F

8. 15 % F D D F C B C C F C F C C D C B C D B B A C A C A B C C B D C A C
Per 1 F D D F C B C C F C F C C D C B C D B B A C A C
Per 2 A B C C B D C A C B B C B A C D C D D D F C C D
Per 3 C D C B B D B C F C D B
15 % C D C D F A D D B A A C
Per 4 B D D C C F A D F F B C B A B C A D B D B F F C
Per 5 A C F B C D F A B B F A C F C F D D A F C B C D

9. 15 % Now find the percent of F’s in your random sample B A C D F D D D
Group A:
15 %
Group B:
Group C:
Group D:
Now find the percent of F’s in your random sample
Group E: B A C D F D D D C D A F D A C B A D B A C C C C B D D F A B F C B C C B C F D B B D B C A C C B A A C B B D F F F F B C C D C D A C A D D B A F A C C D C D B A A C F C B F B D B D B F B F C C D B C C C F D C C F C C C C D C D D B F F B D C