F.1 maths
2008-01-07 4:07 am
There are 18 Ture-orFales questions in a Maths test. 2 marks will be given for each correct answer and 1 mark will be deducted for each wrong answer. If Mimi answers all the questions and gets 24 marks, how many correct answers has she got? Please write down equation.
回答 (3)
2008-01-07 4:25 am
✔ 最佳答案
Answer:Let Mini got X answers correct,
then she got (18 - X) answers wrong.
We have
2X - 1(18 - X) = 24
2X - 18 + X = 24
3X - 18 = 24
3X = 42
X = 14
She got 14 answers correct and 4 answers wrong.
Hope I can Help You!!!
參考: Myself
2008-01-07 4:19 am
let x be the number of correct answers and y be the number of wrong answers:
2x - y = 24 ----------------------------(1)
x + y = 18 -----------------------------(2)
from (2) x = 18 - y -----------------------(3)
sun (3) into (1)
2 (18 - y) - y = 24
36 - 2y - y = 24
12 = 3y
y = 4
sub y into (2)
x + 4 = 18
x = 14
therefore Mimi answer 14 correct answer.
2x - y = 24 ----------------------------(1)
x + y = 18 -----------------------------(2)
from (2) x = 18 - y -----------------------(3)
sun (3) into (1)
2 (18 - y) - y = 24
36 - 2y - y = 24
12 = 3y
y = 4
sub y into (2)
x + 4 = 18
x = 14
therefore Mimi answer 14 correct answer.
參考: myself
收錄日期: 2021-04-13 14:53:31
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