Video lessons with examples and solutions to help Grade 7 students
understand that statistics can be used to gain information about a population by examining
a sample of the population; generalizations about a population from a sample are valid only
if the sample is representative of that population. Understand that random sampling tends to
produce representative samples and support valid inferences.

Common Core: 7.SP.2

- I can draw inferences from a random data sample from a table or graph.
- I can draw inferences from a random data sample without a table or graph.
- I can collect and use multiple samples of data to make generalizations about population.
- I can generate multiple samples of the same size
to gauge the variations in estimates or
predictions.

__Vocabulary____ __

**population:** The entire set of items from which data can be selected.

**
sample:** A selection from a population.

representative sample:

random sample:

**systematic sample: **A sample chosen according to a rule or formula (Example: Survey every 10th person through the door.)

**convenience sample:** A sample that is easiest to reach (Example: Survey the first 10 people through the door.)

**voluntary-response sample:** Members volunteer to be in the sample.

Making Inferences from Data

This Video discusses how to make inferences from a valid survey using proportional reasoning.

Errata in the video: 75 x 10,000 = 750,000, x = 2,500 yellow shoes.

Activity 1:

Below is the data collected from two random samples of 100 students regarding student's school lunch preference.

Make at least two inferences based on the results.

Student |
Tacos |
Hamburgers |
Pizza |
Total |

# 1 | 12 | 14 | 74 | 100 |

#2 | 12 | 11 | 77 | 100 |

Solution:

• Most students prefer pizza.

• More people prefer pizza and hamburgers and tacos combined.

Activity 2:

Given the first name of all students in your grade. Predict the most common name in the U.S. for 7th graders. How good an estimate do you think your sample provides? Explain your reasoning.

Rotate to landscape screen format on a mobile phone or small tablet to use the **Mathway** widget, a free math problem solver that **answers your questions with step-by-step explanations**.

You can use the free Mathway calculator and problem solver below to practice Algebra or other math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.

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