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  Discussion about math, puzzles, games and fun.   Useful symbols: √ ∞ ≠ ≤ ≥ ≈ ⇒ ∈ Δ θ ∴ ∑ ∫ π -




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Topic review (newest first)

2013-10-08 05:34:52


Hope that was okay and welcome to the forum.

2013-10-08 05:27:53

thank you very much wink

2013-10-07 09:19:25


iii) The question is way too general and requires making too many assumptions. If I draw at random from a distribution of any shape and I draw a big sample then the distribution of the sample will approach a normal distribution. They usually pick n = 30.

If I draw a sample of 6 students from this unknown distribution then I will have great difficulty with ii)

The general answer for iii) is that I can get the answer if I know the distribution or if the random sample is 30 or more. This is the best I can do.

2013-10-07 03:40:24

how about iii?
help me please /_\

2013-10-06 20:11:24


ii) .3121

2013-10-06 15:53:07

sorry, part b= part ii

2013-10-04 21:09:03


i) P(27 < X <= 32) = .1972

Under what circumstances can part (b) still be evaluated?

Where is part b?

2013-10-04 21:04:52

dunno Help me plz, thanks wink

A teacher claims that the time (in minutes) required for any HKU student to finish the homework is a normally distributed random variable with a mean of 30 minutes and a standard deviation of 10 minutes.

(i) If a student is randomly selected from HKU, what is the probability that he/she will use more than 27 minutes but less than 32 minutes to finish the homework?

(ii) If a sample of 6 students is randomly selected from HKU, find the probability that the average time of 6 students to finish the homework will be more than 32 minutes?

(iii) Suppose the time (in minutes) required to finish the homework is not a normal random variable. Under what circumstances can part (b) still be evaluated?

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