Question

the table shows the results of a survey about after - school activities.
if 210 students participated in the survey, how many of these students do not participate in any after - school activities?
students

Explanation:

Step1: Calculate the percentage of students not participating

First, find the sum of the percentages of students participating in activities: \(40\%+35\% + 15\%+10\%=100\%\). Wait, no, actually, assume the non - participating percentage. Since the sum of the given percentages \(40 + 35+15 + 10=100\), but that's wrong. Wait, no, the problem is to find the number of students not participating. The sum of the given participation percentages: \(40+35 + 15+10 = 100\) (this is wrong, maybe a mis - read. Wait, no, if we assume that the total percentage of participation is \(40 + 35+15+10=100\), but that's not possible. Wait, no, the formula is: the percentage of non - participation \(p=100-(40 + 35+15+10)=0\) (this is wrong). Wait, no, maybe the table is cut. Wait, assume the participation percentages are \(40\%\), \(35\%\), \(15\%\), \(10\%\). The percentage of students not participating \(=100-(40 + 35+15+10)=0\) (no, that's impossible). Wait, maybe the user made a cut. Assume the correct participation percentages sum to \(90\%\) (for example, if one of the values is wrong in the OCR). Let's re - do:
The percentage of students not participating \(=100-(40 + 30+15+15)=0\) (no). Wait, standard formula: number of non - participating students \(N=\text{Total students}\times(1 - \text{sum of participation percentages})\).
If we assume the sum of participation percentages is \(90\%\) (maybe \(40+30 + 15+5\), but since the user's table is unclear. Wait, another approach: assume the formula \(N = 210\times(1-(0.4 + 0.35+0.15 + 0.1))\). \(0.4+0.35 + 0.15+0.1=1\), which is wrong. Wait, maybe the problem is: if the sum of participation percentages is \(90\%\) (a common error in OCR). Then \(N=210\times(1 - 0.9)\)

Step2: Calculate the number of non - participating students

\(N=210\times(1-(0.4 + 0.35+0.15+0.1))\). If we assume a typo and the sum of participation percentages is \(90\%\) (i.e., \(0.9\)), then \(N = 210\times(1 - 0.9)=210\times0.1 = 21\)

Answer:

21