1. (a) Given a random variable X which is normally distributed with mean 15 and standard deviation 10, find: i. P(X12) iii. P(12

Extracted text: 1. (a) Given a random variable X which is normally distributed with mean 15 and standard deviation 10, find: i. P(X< 20)="" ii.="" p(x="">12) iii. P(12 <>< 20)="" b.="" solve="" the="" equations="" simultaneously="" using="" cramer's="" rule="" x="" -="" 2y="" -="" 3z="0" 3x="" +="" 5y="" +="" 2z="0" 2x="" +="" 3y="" -="" z="2" 2.="" two="" in="" 10="" marketing="" strategies="" randomly="" sampled="" are="" known="" to="" be="" ineffective="" in="" a="" banking="" sector.="" a.="" calculate="" the="" probability="" that="" in="" a="" sample="" of="" 6="" marketing="" strategies="" employed="" in="" the="" banking="" sector:="" i.="" none="" are="" ineffective="" ii.="" more="" than="" half="" are="" ineffective="" b.="" find="" the:="" i.="" expected="" number="" of="" ineffective="" strategies,="" and="" ii.="" standard="" deviation="" of="" ineffective="" strategies="" used="" in="" the="" banking="" sector.="" 3.="" a="" stock="" market="" analysis="" claims="" that="" the="" average="" annual="" retum="" in="" the="" aviation="" sector="" is="" 12%.="" the="" business="" consultant="" want="" to="" test="" whether="" this="" claim="" is="" true.="" the="" business="" consultant="" collected="" a="" random="" sample="" of="" 36="" stocks="" in="" the="" aviation="" sector="" and="" that="" the="" average="" annual="" return="" is="" 10%="" with="" a="" standard="" deviation="" of="" 3%.="" use="" a="" 5%="" level="" of="" significance="" to="" test="" the="" analyst's="">