Inferences and Predictions

The girl will use the ruler to measure the paper for the door decoration.

• Inference

• Observation

• Prediction

A random sample of 80 books at a library showed that 32 books were fiction. Predict the total number of fiction books in a library that has 400 books.

• 160

• 200

• 140

• 120

Answer explanation

To find the total number of fiction books in the library, we can set up a proportion: 32 books out of 80 are fiction, so 400 books would have (32/80) * 400 = 160 fiction books.

In a survey, 45 out of a random sample of 150 people said they prefer tea over coffee. Predict how many people would prefer tea in a city of 30,000 people.

• 9000

• 15000

• 4500

• 12000

Answer explanation

Since 45 out of 150 prefer tea, the ratio is 45/150. Applying this ratio to 30,000 people gives 9000 people who would prefer tea.

A survey on a random sample of 500 people in a city shows that 250 people use public transportation. Predict the number of people using public transportation if the city's population is 10,000.

• 5000

• 2500

• 7500

• 1000

Answer explanation

To predict the number of people using public transportation in a city with a population of 10,000, we can use the ratio from the sample. 250 people out of 500 use public transportation, so in a population of 10,000, we can expect 5000 people to use public transportation.

In a random sample of 60 apples from a farm, 12 apples were found to be rotten. If the farm has 3000 apples, predict the number of rotten apples.

• 600

• 240

• 120

• 480

Answer explanation

To predict the number of rotten apples, use the ratio of rotten apples in the sample to the total apples in the farm: (12/60) * 3000 = 240 rotten apples.

A random sample of 200 people at a concert shows that 120 people are wearing hats. Predict the number of people wearing hats if 800 people are at the concert.

• 480

• 320

• 600

• 400

Answer explanation

To predict the number of people wearing hats for 800 attendees, use the ratio of people wearing hats in the sample. 120/200 = x/800. Solving for x gives 480.

What inference can you draw from this survey?

• I can infer that most students in this school like pizza.

• I can infer that very few students like hamburgers.

• I can infer that their favorite is corn dogs.

• I can infer that most students in this school like hamburgers.