Exam tomorrow, urgent help needed.

Hello, first, im a bulgarian student, my exam is in bulgarian and i translated it to english via google translate, if its not understandable but you are still willing to help excuse me and say so, so I can translate them using the right terminology.

1 task. / A group
To build interval evaluation reliability 0.95 for average daily production assembly line, if it is known that the daily production of this type of line is normally distributed random variable with a standard deviation 0.75 tons and random sample of this SG volume 20 and the calculated average value of average daily 8.855 tons. Find the minimum number of days in which to record the output to an estimate by security 99% and maximum tolerance of 0.25 tons.

2 task / A Group
Introduces a new method for precipitating sugar after the first saturation. The method will be accepted if the quantity of separated sludge / mg / fixed amount of syrup of 2 minutes is greater than 7mg. Lab data
5,2; 5; 2; 5.2; 6.3; 6.3; 6.3; 6.3; 6.8; 6.8; 6.8; 7.5; 7.5; 8.2; 9.1; 9.1; 9.1; 10; 10.
It is estimated also the standard deviation of the sample = 1.59.

1 task / B group
Made a survey of consumers in order to release a new product on the market and appropriately determine its price .Find the interval that with 96% reliability is the price consumers would pay for the goods if the results of the survey have average x (x line) = 47.05, SD = 11.28 and volume n = 38. The data is used as a pilot sample definition of the minimum number of respondents for evaluation interval a user review certainly 99% and maximum tolerance price 2 lev

2 task / B group
B & B Electronics testing a new transformer that must be energized 220V. If supply voltage is significantly different than this value, the transformer will need improvements. Its known that the standard deviation of the voltmeter, which make measurements with 20 V. What decision It must be taken if made tests with 10 transformer of a trial series: 205; 235; 230; 218; 225; 210; 205; 222; 232; 240. How much at least the device must be tested to establish suitability of the new transformer with a significance level of 5% and the power of the criterion 90% .For a significant difference is considered, greater than 10 V.


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