find the sum of all natural numbers between 50 and 150 which are multiples of 6
Answers
Answer:
We have S=S
3
+S
7
−S
21
,
S
3
= Sum of all the number between 200 and 500 which are divisible by 3
S
3
=201+204+...+498
201+[n−1]
3
=498⇒n=100
∴S
3
=
2
100
[201+498]=50×699=34950
S
7
=203+210+...497.
497=303+[n−1]7⇒n=43.
∴S
7
=
2
43
[201+497]=15050
S
21
=210+231+...+483
483=210+[n−1]21⇒n=14
∴S
21
=
2
14
[210+483]=4851
∴S=S
3
+S
7
−S
21
=34950+15050−4851=45149
Step-by-step explanation:
Correct option is
A
45149
We have S=S
3
+S
7
−S
21
,
S
3
= Sum of all the number between 200 and 500 which are divisible by 3
S
3
=201+204+...+498
201+[n−1]
3
=498⇒n=100
∴S
3
=
2
100
[201+498]=50×699=34950
S
7
=203+210+...497.
497=303+[n−1]7⇒n=43.
∴S
7
=
2
43
[201+497]=15050
S
21
=210+231+...+483
483=210+[n−1]21⇒n=14
∴S
21
=
2
14
[210+483]=4851
∴S=S
3
+S
7
−S
21
=34950+15050−4851=45149