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. results are shown in the table below, but some values are missing. fill in the missing values. social media more less total 7th grade 16 8th grade 16 21 total 30

Explanation:

Step1: Find the number of 7th - grade students who spend more than an hour

We know that the total number of students who spend more than an hour is 30, and the number of 8th - grade students who spend more than an hour is 16.
Let \(x\) be the number of 7th - grade students who spend more than an hour. Then \(x+16 = 30\), so \(x=30 - 16=14\).

Step2: Find the total number of 7th - grade students

The number of 7th - grade students who spend less than an hour is 16, and the number of 7th - grade students who spend more than an hour is 14.
The total number of 7th - grade students \(y=14 + 16=30\).

Step3: Find the total number of students who spend less than an hour

The number of 7th - grade students who spend less than an hour is 16, and the number of 8th - grade students who spend less than an hour is 21.
Let \(z\) be the total number of students who spend less than an hour. Then \(z=16 + 21=37\).

Step4: Find the total number of students

The total number of students who spend more than an hour is 30, and the total number of students who spend less than an hour is 37.
Let \(w\) be the total number of students. Then \(w=30+37 = 67\). Also, the total number of 8th - grade students \(=16 + 21=37\)

Answer:

Social Media	More	Less	Total
8th grade	16	21	37
Total	30	37	67