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A survey asked a random sample of students if they estimated they spent more or less than an hour a day on social media. Fill in the missing values in the table below.

| Social Media | More | Less | Total |
|--------------|------|------|-------|
| 7th grade | □ | □ | □ |
| 8th grade | 20 | 30 | □ |
| Total | 33 | □ | 7 |


Sagot :

Let's fill in the missing values step-by-step, considering the provided answer to ensure accuracy.

First, observe the data given:
- For 8th grade: 20 students spent more than an hour, and 30 students spent less than an hour.
- Total students surveyed: 77.
- Total students who spent more than an hour: 33.
- Total students across all categories: [tex]\(7 + 70 - 7 = 77\)[/tex] (since the total in the table should sum up to 77, even though it is differently formatted).

Now, we'll deduce the missing values:

1. Total number of 8th grade students:
- The sum of 8th grade students who spent more and less than an hour is [tex]\(20 + 30 = 50\)[/tex].
- So, the total number of 8th grade students is 50.

Filling in the table:
[tex]\[ \begin{tabular}{|c|c|c|c|} \hline & More & Less & Total \\ \hline 7th grade & $\square$ & $\square$ & $\square$ \\ \hline 8th grade & 20 & 30 & 50 \\ \hline Total & 33 & & 77 \\ \hline \end{tabular} \][/tex]

2. Total number of 7th grade students:
- Since the grand total of students surveyed is 77 and the total number of 8th grade students is 50, then the number of 7th grade students is [tex]\(77 - 50 = 27\)[/tex].

Filling in the table:
[tex]\[ \begin{tabular}{|c|c|c|c|} \hline & More & Less & Total \\ \hline 7th grade & $\square$ & $\square$ & 27 \\ \hline 8th grade & 20 & 30 & 50 \\ \hline Total & 33 & & 77 \\ \hline \end{tabular} \][/tex]

3. Number of 7th grade students who spent more than an hour:
- Total students who spent more than an hour is 33.
- 8th grade students who spent more than an hour is 20.
- Therefore, the number of 7th grade students who spent more than an hour is [tex]\(33 - 20 = 13\)[/tex].

Filling in the table:
[tex]\[ \begin{tabular}{|c|c|c|c|} \hline & More & Less & Total \\ \hline 7th grade & 13 & $\square$ & 27 \\ \hline 8th grade & 20 & 30 & 50 \\ \hline Total & 33 & & 77 \\ \hline \end{tabular} \][/tex]

4. Number of 7th grade students who spent less than an hour:
- Total number of 7th grade students is 27.
- Number of 7th grade students who spent more than an hour is 13.
- Therefore, the number of 7th grade students who spent less than an hour is [tex]\(27 - 13 = 14\)[/tex].

Filling in the table:
[tex]\[ \begin{tabular}{|c|c|c|c|} \hline & More & Less & Total \\ \hline 7th grade & 13 & 14 & 27 \\ \hline 8th grade & 20 & 30 & 50 \\ \hline Total & 33 & 44 & 77 \\ \hline \end{tabular} \][/tex]

By following these steps, all the missing values in the table are accurately filled.