Question

a survey asked a random sample of students if they estimated they spent more or less than an hour a day on social media.

• 24 seventh graders estimated they spent less than an hour.
• 21 eighth graders estimated they spent less than an hour.
• 36 eighth graders were surveyed.
• 77 total students were surveyed.

fill in the missing values in the table below.

social media

	more	less	total
8th grade	\\(\square\\)	\\(\square\\)	\\(\square\\)
total	\\(\square\\)	\\(\square\\)	\\(\square\\)

Explanation:

Step1: Find the number of eighth - graders who spent more than an hour

We know that the total number of eighth - graders surveyed is \(36\), and the number of eighth - graders who spent less than an hour is \(21\).
Using the formula \( \text{More}=\text{Total}-\text{Less}\), we have \(36 - 21=15\)

Step2: Find the number of seventh - graders surveyed

The total number of students surveyed is \(77\), and the number of eighth - graders surveyed is \(36\).
Using the formula \( \text{7th grade total}=\text{Total students}-\text{8th grade total}\), we get \(77 - 36 = 41\)

Step3: Find the number of seventh - graders who spent more than an hour

We know that the number of seventh - graders who spent less than an hour is \(24\), and the total number of seventh - graders is \(41\).
Using the formula \( \text{More}=\text{Total}-\text{Less}\), we have \(41-24 = 17\)

Step4: Find the total number of students who spent less than an hour

The number of seventh - graders who spent less than an hour is \(24\), and the number of eighth - graders who spent less than an hour is \(21\).
Using the formula \( \text{Total less}=\text{7th grade less}+\text{8th grade less}\), we get \(24 + 21=45\)

Step5: Find the total number of students who spent more than an hour

The total number of students is \(77\), and the total number of students who spent less than an hour is \(45\).
Using the formula \( \text{Total more}=\text{Total students}-\text{Total less}\), we have \(77-45 = 32\)

Answer:

Social Media	More	Less	Total
8th grade	15	21	36
Total	32	45	77