Advertisements
Advertisements
Question
In a test, +3 marks are given for every correct answer and –1 mark are given for every incorrect answer. Sona attempted all the questions and scored +20 marks though she got 10 correct answers.
- How many incorrect answers has she attempted?
- How many questions were given in the test?
Advertisements
Solution
i. Total marks scored by Sona = 20
Total correct answers = 10
∴ Marks for correct answers = 10 × 3 = 30
but she got 20 marks.
∴ Marks for incorrect answers = 20 – 30 = –10
–1 mark is given for every incorrect answer.
ii. Total correct answers = 10
Total incorrect answers = 10 ...(From (i) part)
∴ Total questions given in the test = 10 + 10 = 20
APPEARS IN
RELATED QUESTIONS
Find the product, using suitable properties:
26 × (− 48) + (− 48) × (− 36)
Find the product, using suitable properties:
625 × (− 35) + (− 625) × 65
A certain freezing process requires that room temperature be lowered from 40°C at the rate of 5°C every hour. What will be the room temperature 10 hours after the process begins?
Find the following products: (– 18) × (– 10) × 9
Find the following products: (– 20) × (– 2) × (– 5) × 7
Find (– 35) × (– 98).
If Δ is an operation such that for integers a and b we have a Δ b = a × b – 2 × a × b + b × b (–a) × b + b × b then find 4 Δ (–3) Also show that 4 ∆ (–3) ≠ (–3) ∆ 4.
A green grocer had a profit of ₹ 47 on Monday, a loss of ₹ 12 on Tuesday and loss of ₹ 8 on Wednesday. Find his net profit or loss in 3 days.
A multistorey building has 25 floors above the ground level each of height 5 m. It also has 3 floors in the basement each of height 5 m. A lift in building moves at a rate of 1 m/s. If a man starts from 50 m above the ground, how long will it take him to reach at 2nd floor of basement?
If Δ is an operation such that for integers a and b we have a Δ b = a × b – 2 × a × b + b × b (–a) × b + b × b then find (–7) Δ (–1). Also show that (–7) Δ (–1) ≠ (–1) Δ (–7).
