Question

Find the number of integers between 100 and 300 which are divisible by 7 but not by 14

Answer 1

Step-by-step explanation:

we have to find sum of integers between 100 and 300 divisible by 7

now, the first number between 100 and 300 divisible by 7 is 105

therefore, next number will be 105 + 7 i.e 112

and the last number divisible by 7 between 100 and 300 is 294

so, it forms an A.P

now, first term , a = 105

last term , I = 294

and common difference, d=7

now, 294 = 105+7(n-1)

7(n-1)= 294-105

n-1= 189/7

n= 27+1

n= 28

therefore there are 28 terms in thus A.P

now, sum of all terms , S =n(a+I ) /2

S= 28 (105+294)/2

S=14×399

S=5586

hence, sum of terms = 5586

hope it helps you .... pls put me as brainliest answer