In a mathematics competition each correct answer gains 5 marks. However, 1 mark is
deducted for each incorrect answer. Mary answered 30 questions for a total of 78 marks.
Determine the number of correct and incorrect questions Mary answered.
Answers
Answered by
0
Answer:
answer -18 right answer and 12 wrong answer
Answered by
0
Answer:
The number of correct and incorrect questions Mary answered are 18 and 12 respectively.
Step-by-step explanation:
let the correctly answered questions be x and incorrectly answered questions be y.
then marks awarded for correctly answered questions are 5x and marks deducted for incorrectly answered questions are -y.
total question she answered = x + y = 30____(1)
total marks she obtained = 5x - y = 78_____(2)
add (1) and (2), which gives 6x = 108____(3)
from (3) x = 108/6 = 18 substitute this in (1)
then, y = 30 - 18 = 12
Similar questions