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.

• 14 seventh graders estimated they spent more than an hour.
• 21 eighth graders estimated they spent more than an hour.
• 18 eighth graders estimated they spent less than an hour.
• 36 total students estimated they spent less than an hour.

fill in the missing values in the table below.
social media
7th grade
8th grade
total
more less total

Explanation:

Step1: Find the number of seventh - graders who spent less than an hour

We know that the total number of students who spent less than an hour is 36, and 18 eighth - graders spent less than an hour.
Let \(x\) be the number of seventh - graders who spent less than an hour. Then \(x+18 = 36\), so \(x=36 - 18=18\).

Step2: Find the total number of seventh - graders

The number of seventh - graders who spent more than an hour is 14, and the number of seventh - graders who spent less than an hour is 18.
The total number of seventh - graders is \(14 + 18=32\).

Step3: Fill in the eighth - grade values

The number of eighth - graders who spent more than an hour is 21, and the number of eighth - graders who spent less than an hour is 18.
The total number of eighth - graders is \(21+18 = 39\).

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

The number of seventh - graders who spent more than an hour is 14, and the number of eighth - graders who spent more than an hour is 21. So the total number of students who spent more than an hour is \(14 + 21=35\).

Step5: Find the total number of students

The total number of students who spent more than an hour is 35, and the total number of students who spent less than an hour is 36.
The total number of students is \(35+36=71\).

Answer:

Social Media	More	Less	Total
8th grade	21	18	39
Total	35	36	71