Question 30
Let S={1,2,3,…,40}. How many subsets K={a, b, c} of S satisfy a+c=2b?
Original options (preserved):
A. 360
B. 375
C. 380
D. 390
E. 400
Editorial note: Discuss both the three-distinct-elements interpretation and the literal set notation allowing repeated names. Preserve the original options; the rubric is editorial.
Original options (preserved):
A. 360
B. 375
C. 380
D. 390
E. 400
Editorial note: Discuss both the three-distinct-elements interpretation and the literal set notation allowing repeated names. Preserve the original options; the rubric is editorial.