Question 2 :
In a school, students thought of planting trees in and around the school to reduce air pollution. It was decided that the number of trees, that each section of each class will plant, will be the same as the class, in which they are studying, e.g., a section of Class I will plant 1 tree, a section of Class II will plant 2 trees and so on till Class XII. There are three sections of each class. How many trees will be planted by the students?

Question 3 :
Which term of the AP : 121, 117, 113, . . ., is its first negative term?

Question 4 :
Check whether – 150 is a term of the AP : 11, 8, 5, 2 . . .

Question 5 :
The sum of the 4th and 8th terms of an AP is 24 and the sum of the 6th and 10th terms is 44. Find the first three terms of the AP.

Question 6 :
Determine the AP whose third term is 16 and the 7th term exceeds the 5th term by 12.

Question 7 :
An AP consists of 50 terms of which 3rd term is 12 and the last term is 106. Find the 29th term.

Question 8 :
Find the sum of first 51 terms of an AP whose second and third terms are 14 and 18 respectively.

Question 9 :
A contract on construction job specifies a penalty for delay of completion beyond a certain date as follows: Rs 200 for the first day, Rs 250 for the second day, Rs 300 for the third day, etc., the penalty for each succeeding day being Rs 50 more than for the preceding day. How much money the contractor has to pay as penalty, if he has delayed the work by 30 days?

Question 11 :
Find the sum of the following AP: 7 + 10.5 + 14 + . . . + 84

Question 12 :
Find the sum of the odd numbers between 0 and 50.

Question 13 :
If the sum of first 7 terms of an AP is 49 and that of 17 terms is 289, find the sum offirst n terms.

Question 14 :
How many terms of the AP : 9, 17, 25, . . . must be taken to give a sum of 636?

Question 15 :
The 17th term of an AP exceeds its 10th term by 7. Find the common difference.