Use positive and negative integers to total exam marks with negative marking, and to find a company's profit or loss.
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Right answers earn positive marks, wrong ones cost negative marks.
Some tests take marks away for wrong answers. Many entrance exams, such as JEE and NEET, work this way.
Example 1: 30 right and 20 wrong. What is Mala's total?
Problem. An exam has 50 multiple choice questions. Each correct answer gets 5 marks and each wrong answer gets −2 marks. Mala had 30 correct answers and 20 wrong answers. What are her total marks? (Textbook p. 35, Example 1)
Work out how many answers Anita got wrong.
Figure it Out, Textbook p. 43, Q6(a). In a test, marks are given for every correct answer and marks for every incorrect answer. Anita answered all the questions. She scored 40 marks even though 15 of her answers were correct. How many of her answers were incorrect? How many questions are in the test?
List the marks per answer and Anita's numbers.
Multiply.
Compare with her actual score.
Each wrong answer costs 2 marks.
She answered every question.
Anil scored −10 with 5 correct answers. What happened?
Figure it Out, Textbook p. 43, Q6(b). Same test: for correct and for incorrect. Anil scored marks even though he had 5 correct answers. How many of his answers were incorrect? Did he leave any questions unanswered?
The book does not say again how many questions the test has. Use what you found for Anita's test, and say that you did.
Multiply.
Total = correct marks + wrong marks.
Each wrong answer is −2.
Compare with the number of questions in the test.
Score questions in the style of real entrance exams.
A test gives for a correct answer and for a wrong one. Riya gets 20 correct and 8 wrong. Her score?
Profit per item is positive, loss per item is negative.
A shop or company can earn a profit on some items and make a loss on others.
Write a profit as a positive integer and a loss as a negative integer.
3,000 white bags and 5,000 grey bags: profit or loss?
Problem. A cement company earns a profit of ₹8 per bag of white cement and makes a loss of ₹5 per bag of grey cement. In a month it sells 3,000 bags of white cement and 5,000 bags of grey cement. What is its profit or loss? (Textbook p. 39, Q3a)