SAT
Decide who has the smaller margin of error.
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Sample size
The margin of error depends on the number of people sampled.
A larger sample has a smaller margin of error.
Two samples
Priya and Evan each collected data to estimate the percent of people who ate cookies.
Priya sampled 250 people. 40 of them ate cookies.
Evan sampled 60 people. 48 of them ate cookies.
A larger sample has a smaller margin of error.
250 > 60
Priya has the smaller margin of error because more people were sampled.
Evan sampled more people who ate cookies.
48 > 40
That count does not decide the margin of error.
Work these three in a session.
Luis and Maya each collected data to estimate the percent of people who ate cookies.
Luis sampled 50 people. 41 of them ate cookies.
Maya sampled 180 people. 36 of them ate cookies.
Which choice names the person with the smaller margin of error, and why?
The margin of error depends on the number of people sampled.
A larger sample has a smaller margin of error.
Maya sampled 180 people.
Luis sampled 50 people.
180 > 50
Maya has the smaller margin of error because more people were sampled.
Luis sampled more people who ate cookies.
41 > 36
That count does not decide the margin of error.
Answer: B. Maya has the smaller margin of error because more people were sampled.
Nora and Jules each collected data to estimate the percent of people who ride the bus.
Nora sampled 90 people. 82 of them ride the bus.
Jules sampled 400 people. 70 of them ride the bus.
Which choice names the person with the smaller margin of error, and why?
The margin of error depends on the number of people sampled.
A larger sample has a smaller margin of error.
Jules sampled 400 people.
Nora sampled 90 people.
400 > 90
Jules has the smaller margin of error because more people were sampled.
Nora sampled more people who ride the bus.
82 > 70
That count does not decide the margin of error.
Answer: D. Jules has the smaller margin of error because more people were sampled.
Aisha and Ben each collected data to estimate the percent of people who own a dog.
Aisha sampled 150 people. 27 of them own a dog.
Ben sampled 45 people. 39 of them own a dog.
Which choice names the person with the smaller margin of error, and why?
The margin of error depends on the number of people sampled.
A larger sample has a smaller margin of error.
Aisha sampled 150 people.
Ben sampled 45 people.
150 > 45
Aisha has the smaller margin of error because more people were sampled.
Ben sampled more people who own a dog.
39 > 27
That count does not decide the margin of error.
Answer: A. Aisha has the smaller margin of error because more people were sampled.
Try these five on your own.
Camila and Diego each collected data to estimate the percent of people who walk to school.
Camila sampled 75 people. 68 of them walk to school.
Diego sampled 320 people. 64 of them walk to school.
Which choice names the person with the smaller margin of error, and why?
The margin of error depends on the number of people sampled.
A larger sample has a smaller margin of error.
Diego sampled 320 people.
Camila sampled 75 people.
320 > 75
Diego has the smaller margin of error because more people were sampled.
Camila sampled more people who walk to school.
68 > 64
That count does not decide the margin of error.
Answer: C. Diego has the smaller margin of error because more people were sampled.
Finn and Elena each collected data to estimate the percent of people who drink tea.
Finn sampled 80 people. 71 of them drink tea.
Elena sampled 500 people. 40 of them drink tea.
Which choice names the person with the smaller margin of error, and why?
The margin of error depends on the number of people sampled.
A larger sample has a smaller margin of error.
Elena sampled 500 people.
Finn sampled 80 people.
500 > 80
Elena has the smaller margin of error because more people were sampled.
Finn sampled more people who drink tea.
71 > 40
That count does not decide the margin of error.
Answer: A. Elena has the smaller margin of error because more people were sampled.
Hugo and Grace each collected data to estimate the percent of people who take the train.
Hugo sampled 240 people. 48 of them take the train.
Grace sampled 80 people. 70 of them take the train.
Which choice names the person with the smaller margin of error, and why?
The margin of error depends on the number of people sampled.
A larger sample has a smaller margin of error.
Hugo sampled 240 people.
Grace sampled 80 people.
240 > 80
Hugo has the smaller margin of error because more people were sampled.
Grace sampled more people who take the train.
70 > 48
That count does not decide the margin of error.
Answer: D. Hugo has the smaller margin of error because more people were sampled.
Jonah and Iris each collected data to estimate the percent of people who have a library card.
Jonah sampled 80 people. 72 of them have a library card.
Iris sampled 600 people. 50 of them have a library card.
Which choice names the person with the smaller margin of error, and why?
The margin of error depends on the number of people sampled.
A larger sample has a smaller margin of error.
Iris sampled 600 people.
Jonah sampled 80 people.
600 > 80
Iris has the smaller margin of error because more people were sampled.
Jonah sampled more people who have a library card.
72 > 50
That count does not decide the margin of error.
Answer: B. Iris has the smaller margin of error because more people were sampled.
Keira and Leo each collected data to estimate the percent of people who play the piano.
Keira sampled 40 people. 34 of them play the piano.
Leo sampled 200 people. 30 of them play the piano.
Which choice names the person with the smaller margin of error, and why?
The margin of error depends on the number of people sampled.
A larger sample has a smaller margin of error.
Leo sampled 200 people.
Keira sampled 40 people.
200 > 40
Leo has the smaller margin of error because more people were sampled.
Keira sampled more people who play the piano.
34 > 30
That count does not decide the margin of error.
Answer: C. Leo has the smaller margin of error because more people were sampled.
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