Making Inferences with Statistics

Making Predictions & Inferences

You can also use the proportion to make predictions and/or inferences.

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Multiple Choice

The sample is $$200$$  .

there are $$\frac{78}{200}$$   so we can predict how many out of $$28,000$$   by setting up a proportion.

$$\frac{78}{200}=\frac{x}{28,000}$$  

Then cross multiply and divide.

• 10820
• 10920
• 11820
• 11920

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Multiple Choice

First total the number of subscriptions that are represented $$30$$   

there are $$\frac{3}{30}$$  so we can predict how many out of $$250$$   by setting up a proportion. $$\frac{3}{30\ }=\ \frac{x}{250}$$  

 

Then cross multiply and divide.

• 23
• 25
• 35
• 50

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Round to the nearest WHOLE t-shirt.

Multiple Choice

The circle graph shows the results of a survey of teens and where they would prefer to spend a family vacation. Predict how many of 4,000 teens would prefer to go to an amusement park?

Convert the 45% to a decimal $$0.45$$  

Multiply $$0.45\ x\ 4000$$  

• 45 teens

• 889 teens

• 1,300 teens

• 1,800 teens

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Multiple Choice

• More than 50% of the people purchased a hamburger or a sub. 
• Less than 20% of the people purchased a hamburger.
• More people purchased fried rice than chicken.

Multiple Choice

• Less than 5% chose cranberry as their favorite. 
• Less than 1/3 of the students chose grape as their favorite. 
• More than 50% of the students chose apple or orange as their favorite. 
• More than 1/2 of the students chose grape or cramberry as their favorite. 

Multiple Select

• About 40% of the marbles in the bag are red.
• The bag probably contains about 45 yellow marbles.
• There are about twice as many blue marbles than green marbles. 
• There are about three times as many green marbles as there are red marbles.