Advertisements
Advertisements
प्रश्न
Find the sum of all members from 50 to 250 which divisible by 6 and find t13.
Advertisements
उत्तर
The numbers between 50 to 250 which are divisible by 6 are
54, 60, 66 ....246
Here a = 54, d = 6 and tn = 246
tn = a + (n - 1) d
246 = 54 + (n - 1) (6)
246 - 54 = 6n - 6
192 = 6n - 6
192 + 6 = 6n
6n = 198
n = `198/6`
n = 33
Sn = `"n"/2 [t_1 + t_n"]`
S33 = `33/2 [54 + 246]`
= `33/2 [300]`
S33 = 4950
tn = a + (n - 1) d
t13 = 54 + (13 -1) (6)
= 54 + 12(6)
= 54 + 72
t13 = 126
APPEARS IN
संबंधित प्रश्न
The ratio of the sums of m and n terms of an A.P. is m2 : n2. Show that the ratio of the mth and nth terms is (2m – 1) : (2n – 1)
In an AP given a = 8, an = 62, Sn = 210, find n and d.
Find the sum of the odd numbers between 0 and 50.
Find the sum of all 3-digit natural numbers, which are multiples of 11.
Find the middle term of the AP 6, 13, 20, ..., 216.
The 4th term of an AP is 11. The sum of the 5th and 7th terms of this AP is 34. Find its common difference.
If the sum of first n terms is (3n2 + 5n), find its common difference.
Choose the correct alternative answer for the following question .
In an A.P. first two terms are –3, 4 then 21st term is ...
What is the sum of first 10 terms of the A. P. 15,10,5,........?
If the 10th term of an A.P. is 21 and the sum of its first 10 terms is 120, find its nth term.
Write the value of a30 – a10 for the A.P. 4, 9, 14, 19,....
In an AP. Sp = q, Sq = p and Sr denotes the sum of first r terms. Then, Sp+q is equal to
If the first term of an A.P. is a and nth term is b, then its common difference is
Find the value of x, when in the A.P. given below 2 + 6 + 10 + ... + x = 1800.
The sum of the first three numbers in an Arithmetic Progression is 18. If the product of the first and the third term is 5 times the common difference, find the three numbers.
Find the sum of those integers from 1 to 500 which are multiples of 2 or 5.
[Hint (iii) : These numbers will be : multiples of 2 + multiples of 5 – multiples of 2 as well as of 5]
The sum of first five multiples of 3 is ______.
Find the sum of first 20 terms of an A.P. whose nth term is given as an = 5 – 2n.
If the first term of an A.P. is 5, the last term is 15 and the sum of first n terms is 30, then find the value of n.
