yea but for 1, you have to find out whether it is an arithmetic or a geometric series first. so u find out T1, T2 & T3...then u see if T3-T2=T2-T1 or if T3/T2=T2/T1 but it doesnt fit into either...so its not a geo or an arith...unless IM doin something totally wrong...
same with question 3...