MuditKapoor
Hi Bunuel,
Just wanted to confirm one thing, as mentioned in the question begins OR ends OR both therefore shouldn't it contain 3 subsets and based in them 100 numbers which starts , 10 which and 10 that has both
Making it 120.
Please correct me if there is a flaw in the concept.
Bunuel
What is the total number of integers between 200 and 400, each of which either begins with 3 or ends with 3 or both ?
(A) 10
(B) 100
(C) 110
(D) 120
(E) 130
You're counting the third subset (i.e. both begin and end with 3) twice.
First subset: Begins with 3;
3 _ _ = 10 * 9 = 90 numbers (in this case we are omitting nos. ending with 3, since we will count those in third subset)
Second subset: Ends with 3;
2 _
3 = 10 numbers (nos. will begin with 2, the ones that begin with 3, will end with 3 -> they will be counted in third subset)
Third subset: Both Begins and Ends with 3;
3 _
3 = 10 numbers
Now adding all 3 subsets = 10 + 90 + 10 =
110Hope it helps.