Explanation:
The sum is 1225
Solution :
The numbers from 150 to 200 divisible by 7 are 154,161 ,168,…., 196
Here, a=154,d=7a=154,d=7 and tn=196tn=196
tn=a+(n−1)dtn=a+(n-1)d …(Formula )
∴196=154+(n−1)×7∴196=154+(n-1)×7 …(Substituting the values )
∴196−154=(n−1)×7∴196-154=(n-1)×7
∴427=n−1∴427=n-1 ∴n−1=6∴n-1=6 ∴n=7∴n=7
Now, we find the sum of 7 numbers.
Sn=n2[t1+tn]Sn=n2[t1+tn] ...(Formula )
=72[154+196)=72[154+196)
=72×350=72×350
=7×175=7×175
=1225