This is a mix of statistic related questions. Any help is appreciated!! Number 14 is not present as I have been able to answer it.

Question 11 eriicienoy experis study the processes ised to manufaiture items in ordertn make them as efcient as possible. One ofthe steps used to manufacture a metal clamp involves the drilling ofthree holes. In a sample of 84 clamps, the mean time to complete this step was 50.9 seconds. Assume that the population standard deviation is 7 seconds. What is the lower bound of the 98% condent? interval? Round your answer to one decimal place (for example: 41.9). Write only a number as your answer. Question 12 A simple random sample of 12 erreaders or a oertain type had the rolloiinnp minutes of battery lire. 237, 311. 262, 392, 313r 322. 329, 316.. 255, 31a, 315r 291 Assume that it is reasonable to believe that the population is approximately nonnai and the population standard deination is 55. What is the upper bound ofthe 95% condence interval for the battery life for all ereaders or this type? Round your answer to one decimal places (for example: 319.4). Write only a number as your answer. Do not write any units. Question 13 Scientists wantto estimate the mean weight of mice after they have been fed a special diet. From previous studies, it is known that the weight is normally distributed with standard deviation 5 grams. How many mice must be weighed so that a 95% condence interval will have margin ol' error of 0.4 grams? Write only an integer as your answer. Question 15 A iandom sample of13 studenis were asked how long it took them to complete a cereiin exam. The mean length of time was 1112 minutes, with a standard deviation or 74.5 minutes. Find the lower bound or the 90% condence interval iorthe true mean length or time it would lake for all students to mmplete the eiram. Round to one decimal place (For example: 100.1). Write only a number as your answer. Do not write any units. Question 16 Following are interest rates (annual percentage rates) for a 30ryearrxedriate mortgage from a sample of lenders in a certain city. It is reasonable to assume that the population is approximately normal. 4.327, 4.461. 4.547, 4.335 , 4.365. 4.729 ,4.M2 Find the upper bound ofthe 99% condence interval for the mean rate. Round to three decimal places (for example: 4.015). Write only a number as your answer. Do not iiinte any uniis. Question 17 In the computer game World of Worcrai'i'. some of the stnloes are critical strikes. which do more damage. Assume that the probability of a u'itical strike is the same for every attaocr and that attacks are independent. During a partioilar Fight. a charaiter has 264 u'itlcal strikes out of 688 atlacls. What is the lower bound for the 99% condence interval For the proportion of strikes that are critical strikes. Round to three decimal places (for example: 0.419). Write only a number as your answer. Question 18 A udiiity company sampled soc customers, and nds that me ofthem had a disopanoy on their service bill. what is the upper bound for the 99% oonhdenoe interval rorthe proportion or oistomers With a discrepancy on their sennoe bill? Round to three decimal places (for example: 0.419}. Write only a number as your answer. Question 19 A pollster wants to construct a 95% condence interval for the proportion of adults who believe that economic conditions are getting better. A Gallup poll taken in July 2010 estimates this proportion to be 0.33. Using this estimate, what sample size is needed so that the mndence interval Wlll have a margin of error of 0.055 ? Write only an integer as your answer. Question 20 A researcher wants to construct a 99% condence interval For the proportion of people who changed jobs in the past yean what sample size is needed so that the condenoe interval will have a margin of error or p.032 ? Write only an integer as your