I'm not sure what the question is, but if you want to generate 100 values drawn from Weibull distribution with shape parameter of 0.75 use rweibull(100, 0.75)
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If you want to see what the probability is that they are larger than zero, use pweibull(rweibull(100, 0.75), 0.75)
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You should also be aware that there is a general no-homework rule on these sites.