Making Predictions
Using Proportions
Prediction
is a guess about something in the future. One way to make a prediction is to collect information by conducting a survey. The population is the whole group being surveyed. To save time and money, researchers often make predictions based on a sample, which is part of the group being surveyed.
We can use proportions to solve problems about predictions.
We can use proportions to solve problems about predictions.
Example #1
A store claims that 78% of shoppers end up buying something. Out of 1,000 shoppers, how many would you predict buy something?
You can write a proportion. Remember that percent means 'per hundred'.
You can write a proportion. Remember that percent means 'per hundred'.
Set Up the Proportion
Scale Up to Solve
780 People
The store would expect 780 people out of 1,000 shoppers to buy something.
Example #2
Based on a sample survey, a local newspaper states that 3 out of 25 of the city's residents have volunteered at an animal shelter. Out of 5,000 residents, how many would you predict have volunteered at the animal shelter?
Set up a Proportion
Use Cross Products to Solve
600 People
You could predict that 600 residents out of 5,000 have volunteered at the animal shelter.
Practice #1: Now you try.
Based on a sample survey, a local newspaper claims that 64% of the town's households receive their paper. Out of 15,000 households, how many would you predict receive their paper?
Practice #2: Try one more.
Based on a sample survey, 13 out of 50 local people have a pet dog. Out of 600 people, how many people do you predict will have a pet dog?