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6. An electronic store sells a particular model of computer notebooks. There are only four notebooks in stock and the manager wonders what today's demand for this particular model will be. She learns from the marketing department that the probability distribution for x, the daily demand for the laptop, is shown in the table. Find the mean, variance and standard deviation of x. Is it likely that five or more customers will want to buy a laptop today? X 0 1 2 3 4 5 P(X) 0.10 0.40 0.20 0.15 0.10 0.05 7. The heights of 750 students are normally distributed with a mean of 160.5 cm and a standard deviation of 8.8 cm. Assuming that the heights are recorded to the nearest half cm, how many of these students would you expect to have height that is exactly equal to 165 cm. Consider table value of 0.1950 from the computed Z value