Q.

The sum of the common terms of the following three arithmetic progressions. 3, 7, 11, 15, .., 399,

2, 5, 8, 11, ..., 359 and 2, 7, 12, 17, ..., 197, is equal to ________ .                 [2023]


Ans.

(321)

3,7,11,15,,399 are in A.P.

So, common difference d1=7-3=4

2,5,8,11,,359 are in A.P.

Then, d2=5-2=3;  2,7,12,17,,197 are in A.P.

d3=7-2=5

L.C.M. of d1,d2,d3=L.C.M. of (4,3,5)=60

On expanding all A.P.s, common terms are 47,107,167

   Sum=47+107+167=321