Intern
Joined: 21 Aug 2017
Posts: 16
Given Kudos: 9
Location: India
Concentration: Entrepreneurship, Technology
WE:Operations (Other)
Brian got 80 percent of the first 20 questions on the test correct an
[#permalink]
28 Apr 2024, 04:58
We know 80% of 20 is 16. We know Brian answered the remaining questions 100% correct.
Testing option (1), we get 32 total questions. So, subtracting 20 from 32, we get 12, of which he got all correct. Therefore, 16+12=28 is the total number of questions he answered correctly. So option (1) is sufficient.
Testing option (2), we know that total questions answered correctly is 87.5%. So, if total questions is x, then Brian got 0.875x correct answers. On the other hand, we know he got 80% of 20 answers correct and 100% of remaining correct. So this gives us 16+ 100% (x-20) = 0.875x
=> 16 + (x-20)=0.875x
=> 16 + x - 20 = 0.875x
=> -4 + x = 0.875x (going to multiply all terms by 1000)
=> -4000 + 1000x = 875x
=> 1000x-875x = 4000
=> 125x = 4000
=>x=4000/125
=> x=32
So total questions is 32. Out of this, we know the remaining is (32-20)=12. So 16+12=28. Therefore, option (2) on its own is sufficient as well.
Since both options are sufficient on their own, option D is the correct answer.