The 10th term from the end of the A .P., 8,10, 12,........ 126 is
(a) 107 (b) 106 (c) 108 (d) 109
The first term, common difference and last term of an A .P. are 12, 6 and 252 respectively. The sum of all terms is
(a) 5410 (b) 5411 (c) 5412 (d) 5413
The sum of all two digit positive numbers divisible by 3 is
(a) 1664 (b) 1665 (c) 1666 (d) 1600
If a6 – a5 is 200 then the value of a7 – a6 of the same A .P. will be
(a) 100 (b) 400 (c) 200 (d) 300
Find the sum of three numbers is an A .P. is 27 and their product is 405. The numbers are : (a) (3,9,15) (b) (15, 9, 3) (c) both (a) and (b) (d) (3, 9, 12)
Cost of digging the well after 1 metre of digging of Rs. 150 = a4
Cost of digging the well after 2 metres of digging
= Rs. 150 + Rs. 50
= Rs. 200 = a2
Cost of digging the well after 3 metres of digging
= Rs. 150 + Rs. 50
= Rs. 2a = a3
Cost of digging the well after 4 metres of digging
= Rs. 200 + Rs. 50
= Rs. 250 = a4
and so on.
a2 – a4 = Rs. 200 – Rs. 150 = Rs. 50
a3 – a2 = Rs. 250 – Rs. 200 = Rs. 50
a4 – a3 = Rs. 350 – Rs. 250 = Rs. 50
i.e., ak +1 – ak is the same every time.
So this list of numbers forms an A .P. with the first term a Rs. 150 and the common difference d = Rs. 50.