Posted by **sarah** on Saturday, July 20, 2013 at 5:42am.

a quiz has 25 questions with 4points awarded for each correct answer and 1 point deducted for each incorrect answer,with zero for each question omitted.John scores 77points.how many questions did he omit?

- math -
**Reiny**, Saturday, July 20, 2013 at 8:13am
number correct --- x

number incorrect --- y

number skipped ---- 25 - x - y

4x - y + 0(25-x-y) = 77

4x - y = 77

y = 4x - 77

so 4x - 77 ≥ 0 and we also know x+y ≤ 25

4x ≥ 77

x ≥ 77/4 , but x must be an integer

so x ≥20

so we could have

x y (s)kipped

20 3 2

21 7 -2 -----> invalid

22 11 -8 ----> invalide

etc

the only one that will work is

correct 20

wrong 3

skipped 2

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