A number 15 is divided into three parts which are in AP and sum of their squares

A number 15 is divided into three parts which are in AP and sum of their squares is 83. The smallest part is

2) Common difference of sequence 5,8,11,14,… is

3) A.P whose nth term is 2n-1 is

4) The sum of 5 numbers in AP is 30 and sum of their squares is 220. Which of the following is the third term ?

5) 25 trees are planted in a straight line 5 metres apart from each other. To water them the gardener must bring water for each tree separately from a well 10 metres from the first tree in line with the trees. How far will he move in order to water all the trees beginning with the first if he starts from the well ?