Q1-a) The area under the curve of a chi square distribution (19) between 0 and X, is 0.3, then X is equal to: O 10.117 c) O 15.352 The standard deviation of a cigarette's nicotine content is 0. 3 mg....

Plzz explain and solve only a and c question.


Extracted text: Q1-a) The area under the curve of a chi square distribution (19) between 0 and X, is 0.3, then X is equal to: O 10.117 c) O 15.352 The standard deviation of a cigarette's nicotine content is 0. 3 mg. How large sample must be selected if we want to be 95% confident of getting an interval that contains the O 15.119 true mean with a maximum error of 0.03mg: O 9.926 At least 217 At least 139 b) The monthly sales of cars (in L.L) in a show rooms for a company are assumed to follow a normal distribution. A sample of monthly sales has been observed, and given as (in Millions of L.L): At least 216 125 145 88 150 115 183 97 104 125 O At least 385 The confidence interval for the mean sales in all salesrooms, at a 99% level is: (87.37, 157.96) O (97.19, 142.15) O (92.51, 159.05) O (96.63, 144.92)