maths question

[匿名]

2012-09-06 1:08 am

a factory produces two types of shirt:shirt a and shirt b.each type of shirt has 3 sizes: small(s), medium(m) and large(l).the number of shirt a produces and the number of shirt b produced are in ratio 2:3.for each type of shirt,the numbers of shirts ins,m and l sizes are in the ratio 2:5:3.

a)if a shirt is chosen at random,find the probability that it is shirt a in s size.

b)if ashirt is chosen at random and is found to be in s size,find the probability that it is shirt b.

c)if 2 shirts are chosen at random with replacement,find the probabilities that

i)both shirts are of the same type,

ii)both shirts are of the same type and size.

回答 (1)

用戶26340

2012-09-06 6:45 am

✔ 最佳答案

The answer:

a).4/50
=2/25

b).6/10
=3/5

c).
i).20/50*20/50+30/50*30/50
=4/25+9/25
=13/25

ii).(4/50)^2+(10/50)^2+(6/50)^2+(6/50)^2+(15/50)^2+(9/50)^2
=458/2500
=229/1250

I hope the above information would be useful.

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