The owner of a convenience store wants to analyse the sales volume of a certain product. He randomly chooses 8 days, and checks the sales volume of the product in these days. They are as follows. 10 8 11 13 10 12 7 9 Another 32 days are taken randomly. It is found that the sample mean and the sample standard deviation of the sales volume in these 32 days are 12 and 3 respectively. Now, all the selected days are combined as one sample of size 40. (i) Find the sample mean and the sample standard deviation of the sales volume of the product in the combined sample. (ii) If the sales volume is greater than 15 on one day, the owner will store more stock for this product. By considering the unbiased estimates, find the probability of storing more stock. (Give your answers in 4 decimal places if necessary.)
The owner of a convenience store wants to analyse the sales volume of a certain product. He randomly chooses 8 days, and checks the sales volume of the product in these days. They are as follows.
10 8 11 13 10 12 7 9
Another 32 days are taken randomly. It is found that the sample
(i) Find the sample mean and the sample standard deviation of the sales volume of the product in the combined sample.
(ii) If the sales volume is greater than 15 on one day, the owner will store more stock for this product. By considering the unbiased estimates, find the probability of storing more stock.
(Give your answers in 4 decimal places if necessary.)
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