In a computerised test of 50 questions, for each correct answer, 1 mark is awarded, and for each wrong answer, 0.25 marks are deducted. If a student answered the first 35 questions correctly, how many more questions from the remaining 15 should he answer correctly to score 80% given that he attempted all questions brainly
Answers
Answer:
10 is your answer of these questions
Given:
Total number of questions in a test=50
Marking scheme= +1, -0.25
Correct answers=35
Marks to be scored=80%
To find:
The number of questions from the remaining 15 should be answered correctly by him.
Solution:
He should answer 7 more questions correctly from the remaining 15 to score 80% marks.
We can find the number by following the steps given below-
We know that the questions attempted correctly will give him +1 marks and -0.25 for the wrong ones.
The total marks of the test= total number of questions× marks for the correct answer
=50×1
Total marks=50
Questions answered correctly by him=35
80% of the total score=80% of 50
=80×50/100
=40 marks
Marks to be obtained to get an 80% score= 80% of the total score- marks already obtained for correct answers
=40-35
=5
Now, we will use the trial and error method to determine the number of questions to be marked correctly out of the remaining 15.
If he attempts 7 questions correctly and 8 incorrectly, the marks obtained will be as follows-
=(7×1)-(8×0.25)
=7-2
=5
Therefore, the student should answer 7 more questions correctly from the remaining 15 to score 80% marks.