in a class of 40 students, 15 join the computer club, 20 join the science club and 8 join both clubs . if a student is selected at random from the class, find the probability that,
(a) he is a member of the computer club
(b) he is a member computer club but not the science club
(c) he belongs to neither the computer club nor the science club
l want to clear step..
thx...
more about probability
2007-10-07 3:46 am
回答 (2)
2007-10-07 3:55 am
(a) he is a member of the computer club
15/40 x 100% = 37.5%
(b) he is a member computer club but not the science club
(15-8)/40 x 100%=17.5%
(c) he belongs to neither the computer club nor the science club
[40-(15-8+20)] / 40 x 100%=67.5%
2007-10-06 20:48:17 補充：
[40-(15-8+20)] / 40 x 100%=32.5%
2007-10-06 20:48:46 補充：
更正返,c唔係67.5%,係32.5%
15/40 x 100% = 37.5%
(b) he is a member computer club but not the science club
(15-8)/40 x 100%=17.5%
(c) he belongs to neither the computer club nor the science club
[40-(15-8+20)] / 40 x 100%=67.5%
2007-10-06 20:48:17 補充：
[40-(15-8+20)] / 40 x 100%=32.5%
2007-10-06 20:48:46 補充：
更正返,c唔係67.5%,係32.5%
2007-10-07 3:52 am
a) 15/40=3/8
b)(15-8)/40=7/40
c)[(15-8)+(20-8)+8]/40=27/40
b)(15-8)/40=7/40
c)[(15-8)+(20-8)+8]/40=27/40
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