[Q. ] 請教幾題 sets的問題
OG178.
Of the 300 subjects who participated in an experiment using virtual-reality
therapy to reduce their fear of heights, 40 percent experienced sweaty palms,
30 percent experienced vomiting, and 75 percent experienced dizziness. If all
of the subjects experienced at least one of these effects and 35 percent of
the subjects experienced exactly two of these effects, how many of the
subjects experienced only one of these effects?
A. 105
B. 125
C. 130
D. 180
E. 195
答案D
OG的算法我覺得沒有很實用, 可以用偉恩圖嗎? 我有試著用但算不出來...
OG 137.
in Jefferson School, 300 students study French or Spanish or both. If 100 of
these students do not study French, how many of these students study both
French and Spanish?
(1) Of the 300 students, 60 do not study Spanish.
(2) A total of 240 of the students study Spanish.
答案: D
一般若是兩個變數我會偏好用正方圖解較快 (就是類似 OG13的 P.144中間的圖)
但是這題用正方圖解我算不出來, 請問我錯在哪裡呢?
(OG用Venn算得出來, 但我只是想說為何正方圖不行?)
謝謝!
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