Question 35
At a mathematics competition the contestants solved 3 problems. The first problem was solved correctly by $90 \%$ of the contestants, the second by $80 \%$ and the third by $70 \%$ of the contestants. At least what percentage of the contestants solved all three problems correctly?
(A) 30
(B) 35
(C) 40
(D) 50
(E) 70
(A) 30
(B) 35
(C) 40
(D) 50
(E) 70