Veto q&a 7 Month22 (1)

2018
April
@hang out
Q
t1 7
=
4 4
1
4 7
4
Remainder = 3
3
t
2
15
=
3
4 4
4 15
Remainder = 3 12
Answer = 3
3
Sum of the 25 terms of an AP is 400. Find the
13 th term
n
Sum of n terms = ( 2 a+ ( n− 1) d)
= 400
2
25
( 2 a+ (25 − 1) d)
= 400
2
25 ( 2 a+ 24 d)
= 400
2
400×
2
2a+24d =
25
2a+24d = 32
32
a+12d = = 16
2
a+12d = 16
th
13 term = a+12d =16
Q
Q
What is the sum of the 20 consecutive terms of
the AP 10, 15, 20....
Sum of ‘n’ terms
20
= ( 2 × 10 + (20 − 1)5 )
2
n
= ( 2 a+ ( n−1)
d)
2
20
= ( 20 + 19 × 5 )
2
20
= × 95 + 20
2
= 10x115
= 1150
The sum of 10 th term and 20 th term of an AP is
60. What is the sum of 14 th and 16 th term
10 th term = a + 9d
20 th term = a + 19d
Sum = (a + 9d) + (a + 19d) = 60
2a+ 28d = 60 ------ (1)
14 th term = a + 13d
16 th term = a + 15d
Sum = (a + 13d) + (a + 15d)
2a+ 28d - Equation--- (1)
∴2a+ 28d = 60
Selected Previous Year Questions
Q
Q
Find the 15 th term of an arithmatic progression whose
first term is 2 and the common difference is 3
a) 45 b) 38 c) 44 d) 40
ans: c) 44
n th term of AP = a + (n-1)d
= 2 + (15 -1) 3
= 2 + 42 = 44
What is the sum of the first 15 terms of an
AP whose 11 th and 7 th terms are 5.25 and 3.5
respectively
a) 56.25 b) 60 c) 52.5 d) none of these
ans: a) 56.25
a + 10d = 5.25 ------- (1)
a + 6d = 3.25 ------- (2)
(1) - (2) = 4d = 2, d =1/2
a + 5 = 5.25, a = 0.25 = 1/4
15 ⎛ 1 1⎞
S15
= ⎜2× + 14 × ⎟
2 ⎝ 4 2⎠
15 ⎛1 14 ⎞
= ⎜ + ⎟
2 ⎝2 2 ⎠
15 15 225
= × = = 56.25
2 2 4
Q The sum of the first 100 numbers 1 to 100 is
divisible by
a) 1, 2, 4, 8 b) 2 & 4
c) 2 d) none
ans: c) 2
The sum of the first 100 natural numbers is
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