Short type questions (III): 3*1=3 1. In a class test (+ 3) marks are given for every correct answer and (–2) marks are given for every incorrect answer and no marks for not attempting any question. (i) Radhika scored 30 marks. If she has got 12 correct answers, how many questions has she attempted incorrectly? (ii) Mohini scores –5 marks in this test, though she has got 5 correct answers. How many questions has she attempted incorrectly? (iii) Rakesh scores 18 marks by attempting 16 questions. How many questions has he attempted correctly and how many has he attempted incorrectly?
Answers
Answer:
1) Radhika scored 12×3=36 marks. as 3 marks are for correct answer
final score of radhika is 20.
she got 16 marks negative. as −2 marks are for incorrect answer
therefore she made
2
16
=8 incorrect answer.
2) Mohini scored 7×3=21 marks. as 3 marks are for correct answer
final score of radhika is −5.
she got 26 marks negative. as −2 marks are for incorrect answer
therefore she made
2
26
=13 incorrect
Step-by-step explanation:
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Answer:
(i) In a class test,
marks given for every correct answer = 3
marks given for 12 correct answer = 12\times3\ =\ 3612×3 = 36
radhika obtained 20 marks in the class testt
therefore, marks obtained for incorrect answer = 20 -36
= -16
therefore, marks given for one incorrect answer = -2
so, no of incorrect answer = -16\times\frac{-1}{2}\ \ \ =\ 8\−16×
2
−1
= 8
Thus, radhika has attempted = 8 incorrect questions
(ii) Marks given for seven correct answer = 3\times7\ =21\3×7 =21
Mohini scores = -5
Marks obtained for incorrrect answer = -5-21 = -26
now, marks given for one incorrect answer = -2
therefore, no of incorrect answer Mohini has attempted = -26\times\frac{-1}{2}\ \ =13\ incorrect\ question−26×
2
−1
=13 incorrect question