A candy shop makes 5000 candies per day, of which 30% have strawberry flavour. Every Sunday, Jack buys 15 candies randomly. On average, how many of these candies will have strawberry flavour?
Is it just $15*0.3=4.5$? but $4.5$ is not a whole number...so what is the right way?`
Determine the probability that on a given Sunday, there will be at least 6 candies with strawberry flavour that Jack has bought.
$ 1-\mathop{\rm Binomcdf}(15, 0.3 ,5)$ ? Am I right?
In a month of 4 Sundays, what is the probability that Jack will not bring home at least 6 candies with strawberry flavour on any of the Sundays.
$1-\mathop{\rm Binomcdf}(15,0.7,5)$ and multiply 4 times???
Since the sample size of candies is 5,000, I think you are justified in using the binomial and everything that you said looks about right! (If you had a super computer, I think you'd use the hypergeometric) For your third question I'd calculate it as $Binomcdf(15,0.3,5)$ which I am pretty sure is exactly what you wrote, but I am too lazy to double check it.