## anonymous one year ago On a certain multiple-choice test, 9 points are awarded for each correct answer, and 7 points are deducted for each incorrect or unanswered question. Sally received a total score of 0 points on the test. If the test has fewer than 30 questions, how many questions are on the test?

1. DanJS

9*(#correct) - 7*(#wrong) = 0 --given

2. DanJS

there are two variables there and only one equation, need one more to be able to solve

3. anonymous

Cannot be determined 16 19 21 24

4. DanJS

If the test has fewer than 30 questions... that is the second given thing

5. DanJS

Total questions = #correct + #wrong

6. DanJS

which is less than 30

7. campbell_st

just write it as a ratio 9 correct = 7wrong so the ratio is 9:7 16 parts so 7 correct and 9 wrong

8. DanJS

that works

9. anonymous

can we also use 9x7 and 7x9 ?

10. DanJS

what cambell did was take the first equation that was given.. 9*(#correct) - 7*(#wrong) = 0 and solve it as a ratio of correct/wrong

11. DanJS

and the total correct and wrong has to be less than 30

12. anonymous

|dw:1441233943898:dw|

13. DanJS

no...

14. anonymous

yesssssss because 63 -63= 0

15. DanJS

9*(#correct) - 7*(#wrong) = 0 you have to have correct = 7 and wrong = 9, otherwise it is not true

16. DanJS

the correct and wrong answers are worth different points

17. anonymous

yea thats what i did dont u see it?

18. anonymous

9 points for 7 questions which equals to 63 and 7 points for 9 questions which is 63 deducted so total equals 0

19. DanJS

sorry if i read something wrong... this is the summary of it...second

20. DanJS

let: #right = R and # wrong = W --------------------------------- given: 9*R - 7*W = 0 and R + W < 30 --------------------- solve for ratio of R vs W from the first equation... $\frac{ R }{ W }=\frac{ 7 }{ 9 }$

21. anonymous

yea thats what i did. Thank youuuu =)

22. DanJS

with having 7 right and 9 wrong, comes out to zero points...

23. DanJS

7+9 is 16 questions... the next choice is 32 questions, but that is too much . 14 right and 18 wrong

24. DanJS

k welcome