Question

Find the sum of first 50 positive integers which leaves remainder 1 when divided by 7/

Answer 1

8,15,22,29..............50
a=8 , d=7, tn=50
we know that
tn=a+(n-1)d
50=8+(n-1)7
50=8+7n-7
50=1+7n
50-1=7n
49=7n
n=7
we know that
sn=n/2[2a+(n-1)d]
s7=7/2[2(8)+(7-1)7]
we get,
s7=7×29
s7=203
THEREFORE,
the sum of first 50 positive integers which leaves remainder 1 when divided by 7 is 203
hope this helps u