9th 10th 11th 12th | Total

Yes 130 175 122 68 | 495

No 18 34 88 170 | 310

Total 148 209 210 238 | 805

The table contains 805 students in total (which is given in the bottom right, corner of the table), while 130+122+68 = 320 of the 805 students eat regularly in the cafeteria and is not a 10th graders (since 130 is mentioned in the row” Yes” and in the column "9th? of the given table, 122 is mentioned in the row” Yes” and in the column” 11th” ofthe given table, 68 is mentioned in the row ” Yes” and in the column ”12th” of the given table).

The probability is the number of favorable outcomes divided by the number of possible outcomes:

P(Yes and not 10th)=# of favorable outcomes/# of possible outcomes=\(\displaystyle\frac{{320}}{{805}}=\frac{{64}}{{161}}\sim{0.3975}\sim{39.75}\%\)