A quiz of 20 questions awards 7 pts for each correct answer dducts 2 points for each wrong answer and 0 pt for

Question

each question omitted. how many questions did one omitted if he got 87 points? Pls. explain

Answer 1

He answered 13 correctly for 91 points ( 13 x 7 = 91 )
He answered 2 incorrectly for - 4 points
He omitted the remainder ( 5 ) for 0 points.
91 - 4 = 87 points.

Answer 2

Let
a = correct answer
b = wrong answer
c = omitted answer

Two equations:
a + b + c = 20
7a - 2b + 0(c) = 87 or 7a - 2b = 87
Multiply the second equation by 2 to get

2a + 2b + 2c = 40
7a - 2b = 87

now add the equations:
9a + 2c = 127
9a = 127 - 2c
a = (127 - 2c)/9

"a" must be a whole number, so 127 - 2c must be a multiple of 9. remember that 0 <= c <= 20, and 2c is always a multiple of two, so 127 - 2c must be odd.
odd Multiples of 9 less than 127 where 2c is even:
127 - 2(5) = 117
127 - 2(14) = 99
127 - 2(23) = 81
127 - 2(32) = 63
...

Since c < 20, we can limit ourselves to the first two, where c = 5 and c = 14.
If c = 14, then a = 11, and b = -3 but this is extraneous, so the answer is c = 5.

Therefore, he omitted 5 questions.^_^

Answer 3

5 questions omitted.

We know that he answered at least 13 questions correctly, because had he not, he would have obtained less than 87 points even if he omitted every other question. We also know that he could not have gotten 15 or more questions right, because that would imply that he got at least (105-87)/2=9 questions wrong, for a total of 24 questions, and there are only 20 questions on the test. We also know he cannot have gotten 14 questions right, because then his score would be even, regardless of how many questions he got wrong, and it is not. Therefore, he must have gotten exactly 13 questions right, implying that he got (91-87)/2=2 questions wrong, for a total of 15 questions answered. Therefore, he omitted 5 questions.

Answer 4

I believe you wanted an explanation (derivation) as well as the answer.
The answer is 13 correct; 2 wrong; 5 omitted

Let x = the number of correct answers
Let y = the number of wrong answers
Let z = the number of omitted questions

Then (1) 7x -2y = 87 This tells x is odd and at least 13(since 7x12 =84)
Also (2) x+y+z = 20. So y+z <= 7. And since y, z> 0 we must have |z-y|<=5
Adding equations (1) and (2) we have
8x + z -y = 107. But 8x13 = 104, therefore since |z-y|<=5
x must equal 13 (since 15x8=120)
So x=13, y = 2, and z = 5

Answer 5

13 x 7 = 91 (this would have to be an odd number as the point total is odd)
take away 4 = 2 x 2
to get your final total of 87 points

so 15 questions answered altogether (13 correct and 2 wrong) and that leaves 5 omited

Answer 6

He omitted 5 questions since to get a score of 87, one must answer 13 questions correctly, be wrong on two questions and omit 5 questions.

Answer 7

he omitted 5 questions. answered 13 right for 91 points. 7 points x 13 questions. got two wrong at two points each minus . deduct the 2 x 2 from 91 gives you 87.

Answer 8

He got 13 correct, missed 2, and omitted 5.

(Guess and check: it would have to be an odd number to get an odd number of points, and since he got more than half credit (87/140), you just check every odd number between 10 and 20)

Answer 9

how many questions are necessary to get 87 points (less than 20)

if all are correct, how many to get closest to 87
87/7=12.4ish so say 13
13*7=91
91-87=4
how can we minus 4 points?
2 questions wrong.
so total questions is 15

since the test has 20 questions, the number omitted must be 5.

the answer is 5

Answer 10

1. RVD. I have to choose him because his is the only title reign I've seen. I got cable in 2008 so I didn't get to see any ECW when it was on. Too bad they didn't have a ECW version of "Bottom Line" for me to watch. lol 2. Evolution. The way they actually took over the show was great and look at the outcome of their careers(still in progress). They're all multiple world champions. 3.MCMG. They put on displays of how great tagteam wrestling is and could be. No King Of Wrestling on your list? 4. The Dudleys. I think the fact that they're still together made me answer that way as it is a pretty hard choice. 5. Bryan Danielson. My choice overall would have been btwn Danielson and McGuiness because they had some top notch matches against once another and showed what championship matches should look like. 6. Stone Cold Steve Austin. Big fan of him. 7. F. Other: Chris Jericho. Big fan of him as well. 8. Ring Of Honor. Haven't really seen the other promotions listed. 9. Torrie Wilson. Boy, the things I wanted to do to her. 10. Rey Mysterio. He pulled out some amazing maneuvers in his WCW days.